RIDING CONDITIONS

On this section, you will encounter a wide variety of riding conditions from urban to rural while using state highways, county roads and separate bike paths. Many roads will have wide shoulders while others will have none.

Between Hartford and Grafton, IL, the route uses mostly separate bike paths, including the Sam Vadalabene Trail, and road traffic is gen­er­ally fast. The rural area between the Illinois and Mississippi rivers is hilly with blind curves. The narrow roads have no shoulders, and you’ll be riding with heavy and fast commuter traffic during week­days.

From St. Charles westward, the route uses 151 miles of the Katy Trail. This abandoned railroad bed is at river grade and is composed of crushed lime­stone. Depending on the year, keep in mind that flooding of the Katy Trail and adjacent road­ways is possible during late spring/early summer. The cities of Washington and Hermann across the Missouri River are both accessed by new bridges with dedicated pedestrian and bicycle paths.

The Jefferson City Option (54.6 miles) gives you the choice of riding on pavement. There is a bi­cy­cle-pedestrian walkway on the east side of the bridge into Jef­fer­son City. It is used for both directions.

From Lexington through Platte City, the route circles north to avoid Kansas City, and the coun­tryside becomes increasingly urban. The traffic can be heavy and there is little to no shoulder on most roads. This area can be quite hilly as well.

The bridge into Atchison, KS, has 4 lanes and wide shoulders. The route then follows rural roads among rolling grain fields. North of Troy there is very little traffic and there are great views of the Missouri River to the east, with tree-covered bluffs to the west.

The roads in Nebraska generally have good sur­fac­es with little to no shoulder. The route uses 20 miles of the Steamboat Trace north of Brown­ville. Sections of the trail may be closed September-December due to hunting season. The crushed limestone surface is not as smooth as the Katy Trail. At the trail’s end there is a 0.6-mile stretch of gravel road. The bridge at Nebraska City has shoulders. If it is raining, or has rained, the roads and trails can turn muddy and make for very difficult riding.

The Hamburg Option (43 miles) also has a 4.7-mile stretch of dirt road that is virtually unrideable in rainy conditions. The bridge crossing the river east of Brownville is high with no shoul­ders and carries moderate truck traffic.

Riding into Iowa, the route parallels I-29 on a two-lane road with no shoulder and light traffic. A 3.8-mile portion between Percival and Bartlett is gravel. As you get closer to Council Bluffs the riding becomes considerably more urban.

CLIMATE

This section of the route roughly follows the Missouri River across the state of Missouri from the eastern border with Illinois and along the borders with Kansas, Nebraska and Iowa. The continental climate of this area of the country creates summers that are generally hot and humid while spring and fall are mild with moderate tem­peratures. Thun­der­storms are frequent from April through July and occasionally are ac­com­pa­nied by very heavy rains. Tornadoes are a familiar event, most common be­tween March and June.

RIDING CONDITIONS

In general, this route has more on-route gravel than our other road routes. Due to this factor, it is recommended you equip your bicycle with wider than standard road bike tires. Almost without exception, roads are two-lane with no shoulders and surfaces average good to fair condition. This lack of shoulders and the frequent grass and/or gravel verges require good defensive cycling skills.

Be aware of local farm and commuting traffic as you enter the city of Council Bluffs, Iowa. Between Council Bluffs and Sioux City, Iowa, the route parallels I-29 which carries the through traffic. You will want to avoid riding during commuting hours at all costs throughout urban Sioux City.

West of Vermillion, South Dakota, the route has two miles of hard-packed dirt and gravel road. There are multiple gravel access roads to the Missouri River along this section. From Yankton westward, on the state highways, recreational and truck traffic increases. Be aware of boat trailers as well as truck sideview mirrors.

Southwest of Springfield, Niobara is a recommended side trip and can be accessed in one of two ways: 8.5 mi. via all paved roads or 13.7 mi. via The Bottom Rd. which is 6.7 mi. of hard compacted dirt and gravel. Here in South Dakota the Missouri River has been dammed and becomes a string of huge lakes characterized by isolated communities and seasonal services. Ft. Randall Dam is often subjected to high winds. An alternative route is to use the road past the Randall Creek Recreation Area east of the dam to avoid being exposed to the wind.

Just west of Bonesteel, the 25.5-mile Whetstone Bay Option takes you very close to the river. There are no services other than a campground and 14.5 miles of this option are on hard-packed dirt and gravel.

At Fort Thompson you have the choice of riding on either side of the Missouri River into Pierre. Staying on the west side, or south side of the river takes you through the Lower Brule Sioux Indian Reservation and the Fort Pierre National Grassland. West of the town of Lower Brule you’ll find only two primitive campgrounds. The road has steep climbs/descents and dramatic vistas of the river far below. You won’t see many cars here.

To ride the east, or north side of the river, choose the 61-mile Lake Sharpe Option which goes through the Crow Creek Soiux Indian Reservation. Services are also sparse on this option. Traffic is moderate to low with open sight lines and rolling terrain. Pierre is the capital of South Dakota and a major city in the state. Avoid riding during morning and evening rush hours. Traffic will also include recreational and agricultural vehicles.

CLIMATE

This section of the route travels from western Iowa to eastern South Dakota following the Missouri River. The warmest months of the year are predominated by warm, moist air flow from the Gulf Stream in the south. Occasionally, a hot, dry air mass will come in from the deserts of the southwest leading to unusually high temperatures. On average, this area experiences 30 to 40 thunderstorms from late spring to early autumn. These storms are sometimes accompanied by high winds, heavy rain and tornadoes. Damaging hailstorms are frequent through mid-summer. As the route shifts into South Dakota, the wind increases across the open prairie lands. It is most frequently from the south and southeast during the summer.

RIDING CONDITIONS

In general, this route has more on-route gravel than our other road routes. Due to this factor, it is recommended that you equip your bicycle with wider than standard road bike tires. Almost without ex­cep­tion, roads are two-lane with no shoulder and surfaces average good to fair condition. This lack of shoulders and the frequent grass and/or gravel verges require good defensive cycling skills. Beware of “texas tacks,” a variety of thorns sharp enough to cause flat tires, along roadway edges and gravel shoulders.

Recent oil and gas de­vel­op­ment in the Bakken Oil Shale Field of western North Dakota and north­eastern Montana prompt­ed a change in routing in 2012 to avoid the area around Will­is­ton, North Dakota. Because many roads with minimal to no shoul­ders now have high lev­els of truck traffic and are felt to be unsafe for bicyclists, Adventure Cycling changed the route to go through southern North Dakota.

Pierre is the capital of South Dakota and a major city in the state. Avoid riding during the morning and evening rush hours. Traffic can also include rec­re­ation­al and agricultural vehicles, especially from the city northward to Oahe Dam. North of Pierre there is a high, rolling, bluff that affords some great views and open sight lines. The 9.5-mile gravel section between Akaska and Mobridge is wide and well maintained with low traffic volumes. To avoid the gravel section, which can be very muddy when wet, stay on U.S. Highways 83 and 12 through Selby and Glenham.

Note that North Dakota law requires that if a signed bike path or lane is available, bicyclists must use it. If you don’t, you risk getting a ticket.

There are many gravel access roads leading from SR 1804 to reach the Missouri River. The route through the capital city of Bismarck, North Dakota, has two options: one urban through the heart of the city where services are located, and the other on bike paths closer to the river. Avoid riding during rush hours if at all possible. Be careful heading north on River Rd.; the sight lines are short and traffic can be heavy. Once out of the city though, the sight lines open up and offer some great river views and rolling hills with moderate traffic in this agricultural area.

The route heads north toward Stanton and the his­toric sites nearby, then goes south again on sparsely traveled state highways. Near Glen Ullin, the route will follow parallel roads along I-94 to Dickinson. Traffic will increase through towns and in the larger city of Dickinson.

The 50-mile I-94 Cutoff between Bismarck and SR 49 shortens the route by 62.5 miles. You will ride on the wide shoulders on I-94 for 12.8 miles if you take this option.

CLIMATE

As you travel north from South Dakota into North Dakota along the Missouri River, the weather is dominated by continental climate patterns. Rainfall amounts drop as the route progresses westward and high temperatures are accompanied by low humidity.

Thunderstorms and hailstorms are common through­out the summer months of June, July and August and often bring short, hard, rainfalls. These storms also bring with them winds that blow across the open prairie at high speeds, especially near the ground. Shifting winds are, in large part, responsible for the rapid changes in temperature. During the summer, the prevailing winds are southerly in nature, generally with the highest speeds recorded in spring and lowest in late summer.

RIDING CONDITIONS

On this section you’ll be the farthest away from the Expedition’s actual route. Due to the damming of the Missouri River at Fort Peck, Montana, there are no roads along Fort Peck Lake, and only one road crosses the river. The route stays on the south side of the river; the highways on the north side also have sparse services and similar mileages without services.

Highways and roads on this section are two-lane with minimal to no shoulders and surfaces are fair to good.

From Dickinson, North Dakota to Glendive, Montana, the route follows the I-94 freeway corridor. Convenience stores can have unreliable food selections, and post offices can have modified business hours. If you are choosing a mail stop on this map section pick a larger town for delivery. The route here alternates between wide-shouldered I-94 and mostly quiet Old Hwy 10. This highway has very rough pavement occasionally, so ride aware, but it makes a scenic and worthwhile respite from the interstate. In the town of Fryeburg, off route, there is an oil dump. You will encounter a considerable amount of truck traffic on Old Hwy. 10 between Belfield and Fryeburg.

The topography is mostly rolling with exceptions being the hills around Theodore Roosevelt National Park near Medora, North Dakota.

West of Wibaux, between Exits #236 and #224, CR 106’s pavement is in bad shape with severe road cracks. Consider staying on I-94 to avoid the rough ride.

While the scenery typifies “Big Sky Country”, services and vehicles are sparse between Glendive and Lewistown. Plan your ride accordingly and be prepared by carrying extra food and water.

In the towns from Circle to Winnett it’s been reported that citizens don’t drink tap water because it is too alkaline, and can cause disgestive problems. Check locally. Services are limited between Circle and Winnett.

SR 200 is narrow and the grassy shoulder areas frequently drop off. It has stretches of deteriorating pavement, rumble strips, and fast traffic.

Pine trees will be a welcome change from treeless ranchland as you cross the Judith Mountains near Lewistown. SR 200/U.S. 87 into Lewistown is in good condition and though the shoulder width will vary, traffic volume is light. Some of the small towns along SR 81 and 80 before Fort Benton have small general stores.

The descent into Fort Benton on SR 80 is steep and has some sharp curves on rough pavement. Historic Fort Benton, besides being a full service town, is a good place to stop and explore. It is not advised to use U.S. 87 as a shortcut to Great Falls due to high traffic and lack of shoulders.

The route uses lightly traveled county roads to reach Great Falls. Traffic increases on U.S. 87/89 outside of the city, and you’ll ride on a separate bike path along the Missouri River into downtown.

One way to experience the Missouri along this section is to take a hiking or canoe trip through the Upper Missouri River Breaks National Monument. Access to the river is remote and you’ll view what the Expedition saw without roads and power lines, which can still only occur at a few places along their route. Outfitters are found in various towns, and are listed above.

For a side trip, you can choose to ride the 60.7-mile Fort Peck Spur to see one of the world’s largest hydraulic earth-filled dams. When returning to the main route, if you’re riding westbound, be aware that there are no services along the 97-mile stretch between Fort Peck and Jordan. Going eastbound, it is 91.2 miles from Fort Peck to Circle.

CLIMATE

The land of eastern Montana can be characterized as very similar to the Great Plains country. However, you will find that it is broken up by wide valleys and the occasional groups of hills. Due to these open plains, the weather is continental in description. It tends to be dry with great ranges in temperature resulting in hot summer days with cool, comfortable evenings. However, be aware that nearly half of the annual precipitation in this region occurs in the three months of May, June, and July. Much of this summer precipitation is accompanied by severe though brief thunder and hail storms in July and August.

Climate information from Weather America, A Thirty Year Summary of Statistical Weather Data and Rankings, 2001, 2nd edition, Grey House Publishing, Millerton, NY.

RIDING CONDITIONS

In general, the main route on this map section has more on-route gravel than our other road routes. Due to this factor, it is recommended that you equip your bicycle with wider than standard road bike tires. Almost without exception, roads are two-lane with variable shoulder widths and fair surfaces.

Once you leave Great Falls, the next 62.4 miles will be on frontage roads that offer spectacular scenery including near constant views of the Missouri River.

Holter Lake Campground, off route, is a beautiful spot to camp but beware that the 2.4-mi. road leading to the first campground is steep, narrow and rough in addition to being busy on summer weekends. Call in advance to make sure sites are available before making the climb.

North of Helena, the 21.7 mi. Silver City Alternate avoids riding on 16.8 mi. of U.S. 287/I-15 but includes 11.1 mi. of gravel.

Between Townsend and Toston there is a 16.3-mi. gravel alternate, 13 mi. of which is gravel, that allows you to avoid a section of busy U.S. 287. From Toston to the Three Forks turnoff, U.S. 287 carries heavy traffic with variable shoulder widths and rumble stripping.

Though SR 2 has lighter traffic than U.S. 287, the section from Lewis and Clark Caverns State Park to where it intersects with I-90 has narrow spots where you will need to exercise caution. On SR 55 and SR 41 there is moderate to heavy commercial truck traffic.

About 5.2 miles south of Dillon you will need to choose to follow the main route or take the Big Hole Option. The main route (which was Lewis and Clark’s 1805 westbound course) crosses the Continental Divide over Lemhi Pass and includes 24.5 miles of gravel. Traffic is minimal in Montana and increases on U.S. 93 in Idaho north of Salmon. SR 28 and U.S. 93 have minimal shoulder widths.

The paved 87.2-mi. Big Hole Option is the route used by Captain Clark returning eastward in 1806. Traffic is minimal. It is 40.7 miles shorter than the main route. The Gibbons Pass Alternate is gravel/dirt for 15.5 miles. It reconnects with the main route 2 miles south of Sula, Montana.

If you have stayed on the main route, at North Fork you can ride 18.2 miles along the Salmon River to Shoup. Captain Clark made it as far as Indian Creek before deciding the river was unnavigable. Be aware of the rafting traffic and shuttles that uses this road.

North of Sula, large forest fires in the summer of 2000 burned 350,000 acres. U.S. 93 has several narrow stretches south of Darby. The 12.9 mi. Old Darby Alternate has minimal traffic, though U.S. 93 has moderate traffic and wide shoulders.

A separate bike path (and occasional sidewalk) begins 2.8 miles south of Hamilton and continues for 51.6 miles into Missoula. Traffic increases in all the Bitterroot Valley towns, and commuters heading to and from Missoula add to the rush.

CLIMATE

The Rocky Mountains and the Continental Divide play important roles in determining Montana’s climate. East of the Divide, the climate is continental; it is drier with great ranges of temperature. Thundershowers and hailstorms are always a threat on hot summer afternoons, particularly during July and August.

West of the Divide, the state enjoys a semi-marine climate – similar to that of the north Pacific coast, although not as wet. The mountainous terrain in the western third of the state protects the Bitterroot Valley from the cold waves which sweep south from Canada each winter. The same mountains produce the Chinook wind by warming eastbound air as it descends over their slopes from higher elevations. A Chinook can make heavy snow cover disappear in a matter of hours. Overall, Montana has low annual precipitation. Thunderstorms or quick rainshowers are common west of the Divide during the summer.

RIDING CONDITIONS

This section’s route is characterized by riding along creek and river corridors and by climbs and descents between these corridors. The roads used are mostly well-surfaced, but often are narrow with minimal to no shoulders. Traffic will increase near towns and recreational areas.

U.S.12 follows the course of the Lochsa and Clearwater rivers. The highway is narrow, curvy, and shoulderless in stretches, so ride cautiously and defensively. Besides recreational traffic, grain trucks use it as their primary route between Montana and Lewiston, Idaho, the farthest eastern port for the Columbia River system.

At Kamiah, the main route continues to use U.S. 12. While the Idaho Transportation Department and local cyclists do not recommend riding between Kamiah and Lewiston on U.S. 12, we use it for those Lewis and Clark afficionados who want to follow the Expedition’s route as closely as possible. Over the course of the 51 miles between Kamiah and Arrow Bridge there are about 2 miles without shoulders. Please practice defensive riding techniques, ride single file and early in the day, and it’s best to ride this on a weekend. Westbound riders will experience stretches where the roadway is up against concrete barriers with the river on the other side, so there’s no place to bail out. If you are uncomfortable with this type of riding please use the 87.5-mile Palouse Prairie Alternate.

The main route is 19 miles shorter than the Palouse Prairie Alternate. Local cyclists recommended this routing, up and over the Camas and Nezperce prairies, to get to Lewiston and avoid the shoulderless portions of U.S. 12. SR 162 and SR 7 have little traffic, and U.S. 95 has wide shoulders.

Our 138.7-mile Lolo Trail Option is for the enthusiast who is riding with wider tires than the normal width of a touring tire. The rugged, mountainous terrain is reflected in the route profiles. Due to the scarcity of services and water, only fit, experienced cyclists should attempt this. Carrying a water filter is a must and you’ll need to fill up with water wherever you find a source. You are on mostly one-lane narrow gravel/dirt roads until the paved descent into Kamiah at the western end of the option.

The scenic 188-mile Blackfoot Option between Missoula and Great Falls follows the route that Captain Lewis used in 1806 while returning to St. Louis. The option uses two-lane highways that parallel the Blackfoot and Sun rivers. Shoulder widths are variable and traffic is moderate. The 13-mi. unpaved Alice Creek Spur following the creek is shown for those who want to ride, then hike 1.5 miles up to Lewis and Clark Pass to see the vista that Captain Lewis and his men viewed. You can combine the Blackfoot Option with Section 5 to make a loop out of Great Falls.

In Missoula, visit Adventure Cycling’s world headquarters. Enjoy ice cream, a Polaroid photo and free internet access.

Learn more about Missoula at: www.adventurecycling.org/about-us/visit-missoula

OFFICE HOURS: Open 8 AM-5 PM Monday-Friday, closed weekends and holidays. Located at 150 E. Pine St., 721-1776

CLIMATE

Comprising rugged mountain ranges, canyons, high grassy valleys, arid plains, and fertile lowlands, Idaho reflects in its topography and vegetation a wide range of climates. Located some 300 miles from the Pacific Ocean, Idaho is, nevertheless, influenced by maritime air borne eastward on the prevailing westerly winds. This maritime influence is most marked in the northern part of the state, where the air arrives via the Columbia River Gorge with a greater burden of moisture than at lower latitudes. In summer, periods of extreme heat extending beyond a week are quite rare. The incidence of summer thunderstorms is greatest in mountainous areas.

In Montana, the Continental Divide exerts a marked influence on the climate of adjacent areas. West of the Divide the climate is a modified north Pacific coast type, while to the east, climatic characteristics are decidedly continental. During the summer months hot weather occurs fairly often east of the Divide. Hot spells never become opressive though, because summer nights almost invariably are cool and pleasant. Areas adjacent to mountain ranges in general receive the most precipitation. Severe thundershowers with accompanying hail occur mostly in July and August.

RIDING CONDITIONS

U.S. Bicycle Route (USBR) 20 has been designated in Washington. Portions of our route run concurrent with it. For more information and maps see advcy.link/wausbr.

From Clarkston, Washington, the route follows U.S. 12, which has light traffic and intermittent shoulders. These conditions continue into Oregon.

Once the route starts following the Columbia River winds can become fierce, particularly in the Columbia River Gorge area, while blowing predominately from the west.

West of Touchet, Byrnes Rd. offers some more off-highway riding if you don’t mind some gravel. It is 0.8 mi. longer than the main route, and the gravel is well-maintained and hard-packed.

In July and August, during harvesting season, Middle Waitsburg Rd. can carry grain truck traffic. Between Waitsburg and Walla Walla U.S. 12 may be a suitable alternative to Middle Waitsburg Rd. It is 1.6 mi. longer, is slightly less hilly, has variable shoulder widths and a centerline rumblestrip but longer sightlines.

In Washington, SR 14 has light traffic with occasional large trucks. Services on SR 14 in eastern Washington are few and far between, so plan accordingly. As you approach U.S. 197, you will have a choice of cycling on either side of the river to continue westward.

The 84.1-mile Washington Option has fewer services. Traffic on SR 14, especially truck traffic, will increase as you head west. The highway has intermittent shoulders. A series of five tunnels have buttons to activate “Bikes in Tunnel” lights. From Prindle, rural roads offer a respite from SR 14 through Washougal and Camas. These roads have little shoulder but carry far less traffic. As the route approaches Vancouver on SE Evergreen Hwy., the pavement is poor, but traffic levels are light.

On the Oregon side, the route crosses the Columbia River on U.S. 197, which has a sidewalk on the east side of the bridge. The route joins the Riverfront Trail at The Dalles and then U.S. 30, also known as the Historic Columbia River Hwy., west of The Dalles. U.S. 30 is a two-lane road with intermittent shoulders. Traffic is light to moderate and the pavement is good.

West of Hood River, the route follows I-84 for 6 miles. The rumble strips on I-84 are deep, so ride carefully when crossing them. There are many state recreation areas along the I-84 corridor which are useful when stopping for a break.

There are two sections of the Historic Columbia River Hwy. that are now closed to vehicles and are designated as a state trail. The second one, west of Cascade Locks, is a paved bike path with a three-story staircase. There is a wheel-groove for bicycles, but it is next to a handrail and depending on the size of your panniers, you might have to take them off. A map is available at: advcy.link/HistColRivStateTrl.

U.S. 30 has some some blind curves between Ainsworth State Park and Troutdale. The traffic also gets heavier, but it is generally slow-moving.

Portland is one of the most bicycle-friendly cities in the country. The route into downtown Portland is a mostly signed bicycle route and local traffic is very aware of cyclists. Both the Amtrak and the Greyhound bus stations are located at Union Station on the south side of the Broadway Bridge crossing. U.S. 30 is a signed bike route all the way to Astoria. It can carry heavy traffic and the shoulder is intermittent. Use extra caution at the multiple creek crossings as the shoulder can completely disappear. Intermittently, the Astoria Riverwalk consists of planks running in the direction of travel. Beware the gaps between planks with narrow tires.

An alternate route from Portland to Astoria, as well as other northwest Oregon route resources, can be found at: advcy.link/NWOregonMaps.

The remaining miles take you past Lewis & Clark National Historical Park into Seaside, where the Expedition processed seawater into salt.

The 19.3-mile Cape Disappointment Spur uses the Astoria-Megler Bridge to cross the mouth of the Columbia River. This narrow, tall two-lane bridge carries moderate to heavy traffic, especially on weekends. Winds can be severe, so use caution. U.S. 101 on the Washington side carries light to heavy traffic on the weekends. The surface is excellent and it has intermittent shoulders.

All known Amtrak stations are listed on this map but not all stations provide bicycle service. Check if bicycle service is provided at both the starting and ending stations on your trip using the spreadsheet and other trip planning resources at advcy.link/amtrak.

CLIMATE

The route in eastern Washington is shielded from the moist air of the coast by the Cascade Mountain Range. This accounts for the low relative humidity and high temperatures that can be common in the summer. Once into Oregon, the Columbia River Gorge offers ready passage of marine air from the Pacific. This generally moderates the potentially high temperatures that can be found along this route in the eastern part of the state. As you approach the coast, and the single most important geographic feature of the climate – the Pacific Ocean, the temperatures can fall while the chance of precipitation rises.

RIDING CONDITIONS

This map section follows the eastbound route that Captain Clark and most of the Expedition traveled in 1806 in an attempt to cover more territory. In general, our route stays on I-90 and the frontage roads that parallel it. The route is slightly rolling with great views of the Yellowstone River.

The frontage roads are signed as “Frontage Rd.” on most map panels, but the signs on the roadways can vary. A number of locals will refer to it as “old Highway 10”. In towns Frontage Roads change to other street names but the route is usually still on the same road.

The frontage road for the most part is a great road for touring cyclists. The road surface and shoulder widths can vary greatly. The interstate carries all of the high-speed traffic, however, leaving the frontage and rural secondary roads available for cyclists.

Between Bozeman and Glendive the route occasionally uses the interstate when there is no frontage road. Use caution when entering and exiting the ramps, as most of them have cattleguards. The interstate does have a wide shoulder and carries light traffic as far as interstates go, but use caution as the traffic does travel at high speed. Keep a keen eye out for debris on the shoulder of the interstate, especially the belts from tractor trailer tires that have disintegrated, as this can wreak havoc with bicycle tires.

You’ll have a gentle climb over Bozeman Pass to get into the Yellowstone River drainage. Bozeman and Billings are the largest towns the route goes through, but riding through each is simple and straightforward. Billings is the largest city in the state.

Remember that riding on the interstate can leave you exposed to the elements as well as the traffic. Be prepared for large wind gusts that can change direction at any moment, especially in the country surrounding Livingston and Big Timber.

Services can be few and far between the farther east the route goes. Take time to fill your water bottles at each opportunity.

CLIMATE

As you travel east along the Yellowstone River, the principal tributary of the Missouri River in Montana, the weather is dominated by continental climate patterns. During the summer months hot weather occurs fairly often, with temperatures oc­ca­sionally reaching 100 degrees. Hot spells do not become oppressive, however, because summer nights are almost invariably cool and pleasant. Rainstorms can be few and far between the farther east you travel, though nearly half of the average yearly total falls in the two months from May to June. Thunderstorms can occur during the months of June, July and August, and can contain large-sized hail. These storms also bring with them winds that blow across the open prairie at high speeds, especially near the ground. Tornadoes develop infrequently, but can occur in this section of the state. Drought in its most severe form is practically unknown, but dry years do occur in some sections.