Question: The Dearborn River is a tributary of the Missouri River, in central Montana, it rises in western Lewis and Clark County, is a county located in Montana, in which country?
Context: The Judith River is a tributary of the Missouri River, approximately 124 mi (200 km) long, running through central Montana in the United States.  It rises in the Little Belt Mountains and flows northeast past Utica and Hobson.  It is joined by Dry Wolf Creek in northern Fergus County, and itself joins the Missouri in the White Cliffs Area approximately 18 mi (29 km) northwest of Winifred. Smith River is a tributary of the Missouri River, in central Montana, in the United States.  It rises in southern Meagher County in the Castle Mountains and flows northwest in the valley between the Big Belt and Little Belt mountains, past White Sulphur Springs and past Smith River State Park.  It turns north-northwest (NNW), and is joined by Hound Creek in Cascade County, and joins the Missouri approximately 9 mi southwest of Great Falls. The Lewis and Clark Bridge is a historic bridge in Wolf Point, Montana, which once carried Montana Highway 13 across the Missouri River between McCone and Roosevelt counties.  It is also known as Wolf Point Bridge, Missouri River Bridge, or Site No. 24RV438.  The bridge is a five-span Pennsylvania through truss; its longest span is the longest through truss span in the state at 400 ft .  Completed in 1930 by the Missouri Valley Bridge and Iron Company, the bridge was the first bridge across the Missouri River at Wolf Point and the only bridge along the river for a 350 mi stretch.  The bridge's opening ceremony, which took place on July 9, drew over 10,000 visitors and included five bands and a fireworks display.  After its completion, the bridge became a popular tourist attraction for motorists in northeastern Montana and a point of civic pride for Wolf Point's residents. Cow Creek is a tributary of the Missouri River, approximately 35 mi long, in north central Montana in the United States.  Cow Creek rises in the southern foothills of the Bear Paw Mountains in western Blaine County and flows east and then south, joining the Missouri approximately 25 mi northeast of Winifred, Montana—or 22 mi upstream from the Fred Robinson Bridge.  Cow Creek flows down to the Missouri in a canyon that passes through the Missouri Breaks, which are severely eroded badlands that extend out on either side from the Missouri River.  The floor of Cow Creek canyon provided a pathway of travel from the Montana plains north of the river, down to the Missouri – at the mouth of Cow Creek, Cow Island made fording the Missouri easier – a steep but short trail on the south bank of the Missouri opposite Cow Creek completed this route which led from the northern Montana plains to the central and southern Montana plains.  This pathway was used by migrating buffalo/bison and nomadic American Natives for centuries.  During the steamboat era on the Missouri River, when low water prevented riverboats getting up to Fort Benton, the mouth of Cow Creek became a river landing and freighting depot, and it was the start of the Cow Island Trail by which freight was moved on to Fort Benton by going north up Cow Creek and then west.  In 1877 the Nez Perce Indian Tribe, fleeing to Canada, had several skirmishes along Cow Creek including the "Battle of Cow Island", and several days later at a camp on Cow Creek the Nez Perce, thinking themselves now beyond the reach of the U.S. Army, made the fateful decision to slow down, rather than push on for the Canada–US border.  Today, modern highways have by passed Cow Creek, and the buffalo and the nomadic Indian are gone.  Cow Creek is dormant, in one of the most remote spots of the isolated regions of the vast area known as the Montana Missouri Breaks. Lewis and Clark Pass, el.  6424 ft is a mountain pass on the continental divide in Montana.  It lies at the head of the drainages of the west flowing Blackfoot River and the east flowing Dearborn River.  The pass is in the Helena National Forest in Lewis and Clark County.  The Continental Divide Trail traverses north and south through the pass.  At the time of the Lewis and Clark Expedition the pass was a much-used pathway where the native people living in what today is Montana crossed over the continental divide.  The pass was crossed by Meriwether Lewis on July 7, 1806, on the return leg of the Lewis and Clark Expedition with a party of nine men and his dog Seaman.  The pass was named for the expedition's two leaders–Lewis and William Clark.  Lewis and Clark Pass is the only roadless pass on the entire Lewis and Clark National Historic Trail.  It has gone from being one of the most used continental divide passes prior to the pioneer era to one of the least visited passes today.  It can be accessed by a 1.5 mi trail.  Visitors will encounter the pass much as Lewis did in 1806.  The furrows left by the countless dog and horse travois that crossed the pass are still visible (though fading) and this is one of the places along the expedition's route that visitors may still encounter a grizzly bear.  On a clear day, like Meriwether Lewis in 1806 one can see Square Butte in Cascade County, Montana, 40 mi to the northeast. The Cracon du Nez (also known as Gross Condunez) occasionally also misspelled (on Google Maps and Google Earth) as the Crocon du Nez, is a sharp sided ridge that divides the Teton River and the Missouri River in Chouteau County, Montana (47.874719° -110.598212°), at a point where the increasing erosion at a large bend of the Missouri River has caused the two rivers to be a mere third of a mile (about 650 yards) apart.  The Cracon du Nez ridge is an example of Missouri River stream bank erosion developing toward a future "stream capture" of the Teton River flow.  A trail runs along the top of the ridge, where in 1865 Little Dog, a chief of the Piegan Blackfoot tribe was ambushed and killed by rebellious and jealous warriors from his own Piegan band.  An abandoned railroad tunnel runs under the ridge, part of the former Montana Central Railway branch line of the Great Northern railroad running from Havre to Fort Benton, Great Falls, Helena and Butte.  U.S. Highway 87 passes by the ridge and allows the traveler to see the Cracon du Nez.  The name is derived from the French and means bridge of the nose, and was probably given by the French boatmen who comprised keelboat crews in the fur trade in the upper Missouri River in Montana during the early decades of the 1800s. Lewis and Clark County is a county located in the U.S. state of Montana.  As of the 2010 census, the population was 63,395.  Its county seat is Helena, the state capital.  The numerical designation for Lewis and Clark County (used in the issuance of the state's license plates) is 5.  The county was established in 1865 as Edgerton County, and was renamed "Lewis and Clark County" two years later.  The present name was given in honor of explorers Lewis and Clark. The 2011 Missouri River floods was a flooding event on the Missouri River in the United States.  The flooding was triggered by record snowfall in the Rocky Mountains of Montana and Wyoming along with near-record spring rainfall in central and eastern Montana.  All six major dams along the Missouri River released record amounts of water to prevent overflow which led to flooding threatening several towns and cities along the river from Montana to Missouri; in particular Bismarck, North Dakota; Pierre, South Dakota; Dakota Dunes, South Dakota; South Sioux City, Nebraska, Sioux City, Iowa; Omaha, Nebraska; Council Bluffs, Iowa; Kansas City, Missouri; Jefferson City, Missouri, as well as putting many smaller towns at risk.  According to the National Weather Service, in the second half of the month of May 2011, almost a year's worth of rain fell over the upper Missouri River basin.  Extremely heavy rainfall in conjunction with an estimated 212 percent of normal snowpack in the Rocky Mountains contributed to this flooding event. The Dearborn River is a tributary of the Missouri River, approximately 70 mi (113 km) long, in central Montana in the United States.  It rises in the Lewis and Clark National Forest, near Scapegoat Mountain in the Lewis and Clark Range of the Rocky Mountains at the continental divide, in western Lewis and Clark County.  It flows generally southeast through secluded canyons, and joins the Missouri near Craig. The Red Rock River is a roughly 70 mi river in southwestern Montana in the United States.  Its drainage basin covers over 1548 mi2 .  Its furthest tributary, Hell Roaring Creek, originates in the Beaverhead National Forest within a few hundred meters of the North American Continental Divide and Montana-Idaho border near Brower's Spring, at an elevation of about 9100 ft .  Brower's Spring is near the furthest headwaters of the Missouri River, one of the major watercourses of the central United States.  The drainage flows north and west with its name changing to "Red Rock Creek" into the Red Rock Lakes in the middle of a wide grassy valley; the Red Rock River issues from the west side of Lower Red Rock Lake.  It flows west, receiving many tributaries such as Peet Creek and Long Creek, widening into the Lima Reservoir and then passing through a canyon, which ends near Lima, Montana.  From there, it flows northwest through a valley, passing Kidd and Red Rock, and into Clark Canyon Reservoir.  Under the waters of the lake was once the confluence of the Red Rock and Horse Prairie Creek, forming the Beaverhead River, a tributary of the Jefferson River, in turn a headwater of the Missouri River.
Answer: United States