Question: What is the population of Williston in the state where Yellowstone meets the Missouri River?

full_context: Document 1: Boulder River (Sweet Grass County, Montana): The Boulder River is a tributary of the Yellowstone River, approximately 60 mi (96 km) long, in south central Montana in the United States. It is one of two rivers named the Boulder River in Montana.
Document 2: Fargo, North Dakota: Fargo is the most populous city in the state of North Dakota, accounting for over 15% of the state population. Fargo is also the county seat of Cass County. According to the 2016 United States Census estimates, its population was 120,762, making it the 229th-most populous city in the United States. Fargo, along with its twin city of Moorhead, Minnesota, as well as the adjacent cities of West Fargo, North Dakota and Dilworth, Minnesota, form the core of the Fargo - Moorhead, ND - MN Metropolitan Statistical Area, which in 2016 contained a population of 238,124. In 2014, Forbes magazine ranked Fargo as the fourth fastest - growing small city in the United States.
Document 3: Dallas: Dallas (/ ˈdæləs /) is a city in the U.S. state of Texas. It is the most populous city in the Dallas -- Fort Worth metroplex, which is the fourth most populous metropolitan area in the United States. The city's population ranks ninth in the U.S. and third in Texas after Houston and San Antonio. The city's prominence arose from its historical importance as a center for the oil and cotton industries, and its position along numerous railroad lines. The bulk of the city is in Dallas County, of which it is the county seat; however, sections of the city are located in Collin, Denton, Kaufman, and Rockwall counties. According to the 2010 United States Census, the city had a population of 1,197,816. The United States Census Bureau's estimate for the city's population increased to 1,317,929 as of July 1, 2016.
Document 4: Montana: The northern section of the Divide, where the mountains give way rapidly to prairie, is part of the Rocky Mountain Front. The front is most pronounced in the Lewis Range, located primarily in Glacier National Park. Due to the configuration of mountain ranges in Glacier National Park, the Northern Divide (which begins in Alaska's Seward Peninsula) crosses this region and turns east in Montana at Triple Divide Peak. It causes the Waterton River, Belly, and Saint Mary rivers to flow north into Alberta, Canada. There they join the Saskatchewan River, which ultimately empties into Hudson Bay.
Document 5: Montana: The United States Census Bureau estimates that the population of Montana was 1,032,949 on July 1, 2015, a 4.40% increase since the 2010 United States Census. The 2010 census put Montana's population at 989,415 which is an increase of 43,534 people, or 4.40 percent, since 2010. During the first decade of the new century, growth was mainly concentrated in Montana's seven largest counties, with the highest percentage growth in Gallatin County, which saw a 32 percent increase in its population from 2000-2010. The city seeing the largest percentage growth was Kalispell with 40.1 percent, and the city with the largest increase in actual residents was Billings with an increase in population of 14,323 from 2000-2010.
Document 6: Stillwater River (Stillwater County, Montana): The Stillwater River is a tributary of the Yellowstone River. Approximately 70 miles (113 km) long, it runs through southern Montana in the United States.
Document 7: Williston, Florida: Williston is a city in Levy County, Florida, United States. As of the 2010 census it had a population of 2,768. The city was established before 1885 by J. M. Willis, who named it after himself.
Document 8: Zahl, North Dakota: Zahl is an unincorporated community in northwestern Williams County, North Dakota, United States. It lies along North Dakota Highway 50 north of the city of Williston, the county seat of Williams County. Its elevation is 2,014 feet (614 m). Although it is unincorporated, it has a post office, with the ZIP code of 58856.
Document 9: Williston, North Dakota: Williston is a city in and the county seat of Williams County, North Dakota, United States. The 2010 census gave its population as 14,716, and the Census Bureau gave the 2015 estimated population as 26,977, making Williston the sixth largest city in North Dakota. The North Dakota oil boom is largely responsible for the sharp increase in population.
Document 10: Gallatin River: The Gallatin River is a tributary of the Missouri River, approximately 120 mi (193 km long), in the U.S. states of Wyoming and Montana. It is one of three rivers, along with the Jefferson and Madison, that converge near Three Forks, Montana, to form the Missouri.
Document 11: Gardner River: The Gardner River (also known as the Gardiner River) is a tributary of the Yellowstone River, approximately long, in northwestern Wyoming and south central Montana in the United States. The entire river is located within Yellowstone National Park. It rises on the slope of Joseph Peak, Gallatin Range in the northwestern part of the park, and winds southeast through Gardner's Hole, a broad subalpine basin which is a popular trout fishing location. Angling on the Gardner is governed by Yellowstone National Park fishing regulations. After merging with Panther Creek, Indian Creek and Obsidian Creek, it then turns north and flows through a steep canyon where it cuts through a basaltic flow from approximately 500,000 years ago known as Sheepeater Cliffs. Below Sheepeater, Glen Creek out of Golden Gate Canyon and Lava Creek out of Lava Creek Canyon join the Gardner near Mammoth Hot Springs. The river crosses the 45th parallel in Gardner Canyon and is also home to a popular hot spring known as "The Boiling River". The river continues north through Gardner Canyon and empties into the Yellowstone near Gardiner, Montana.
Document 12: Missouri River: The Missouri River is the longest river in North America. Rising in the Rocky Mountains of western Montana, the Missouri flows east and south for 2,341 miles (3,767 km) before entering the Mississippi River north of St. Louis, Missouri. The river takes drainage from a sparsely populated, semi-arid watershed of more than half a million square miles (1,300,000 km), which includes parts of ten U.S. states and two Canadian provinces. When combined with the lower Mississippi River, it forms the world's fourth longest river system.
Document 13: Montana: The Yellowstone River rises on the continental divide near Younts Peak in Wyoming's Teton Wilderness. It flows north through Yellowstone National Park, enters Montana near Gardiner, and passes through the Paradise Valley to Livingston. It then flows northeasterly across the state through Billings, Miles City, Glendive, and Sidney. The Yellowstone joins the Missouri in North Dakota just east of Fort Union. It is the longest undammed, free-flowing river in the contiguous United States, and drains about a quarter of Montana (36,000 square miles (93,000 km2)).
Document 14: Montana: East of the divide the Missouri River, which is formed by the confluence of the Jefferson, Madison and Gallatin rivers near Three Forks, flows due north through the west-central part of the state to Great Falls. From this point, it then flows generally east through fairly flat agricultural land and the Missouri Breaks to Fort Peck reservoir. The stretch of river between Fort Benton and the Fred Robinson Bridge at the western boundary of Fort Peck Reservoir was designated a National Wild and Scenic River in 1976. The Missouri enters North Dakota near Fort Union, having drained more than half the land area of Montana (82,000 square miles (210,000 km2)). Nearly one-third of the Missouri River in Montana lies behind 10 dams: Toston, Canyon Ferry, Hauser, Holter, Black Eagle, Rainbow, Cochrane, Ryan, Morony, and Fort Peck.
Document 15: Wilton, North Dakota: Wilton is a city in Burleigh and McLean counties in the State of North Dakota. It is part of the "Bismarck, ND Metropolitan Statistical Area" or "Bismarck-Mandan". The population was 711 at the 2010 census. Founded in 1899, Wilton was named by General W. D. Washburn after the town of Wilton in his native state of Maine.
ground_truth: 26,977
sub_queries: Where does the Yellowstone meet the Missouri river? Answer: North Dakota
what is the population of williston North Dakota Answer: 26,977