northeastern Nebraska. European settlement On July 21, 1804, the Lewis and Clark Expedition passed by the riverbanks that would later become the city of Omaha. On July 22 the Corps of Discovery established a camp near present-day Bellevue for five nights, naming it "Camp White Catfish." On the 27th, William Clark and Reuben Fields investigated mysterious earthen mounds close to where 8th and Douglas Streets and the Heartland of America Park are today in Downtown Omaha. That night they camped in an area that is Eppley Airfield today. The expedition stopped at a point about 20 miles (30 km) north of present-day Omaha, at which point they first met with the Otoe. They had a council meeting with members of the tribal leadership on the west side of the Missouri River. The first recorded instance of a black person in the Omaha area was "York", an enslaved African American who accompanied William Clark on the Expedition. The Astor Expedition came through in 1811. Stephen Long passed through the Omaha area in 1819 on his Platte River Expedition. A decade later, adventurers and fur traders were frequenting the region, trading at Fort Lisa, built by Manuel Lisa in 1806; Fort Atkinson, built in 1819 as a military outpost adjacent to the location of the earlier council meeting; and Cabanne's Trading Post, built by the American Fur Company in 1822. In 1825 a fur trader named J.B. Royce built a stockade and trading post on a plateau near the present-day block formed by Dodge Street and Capitol Avenue, Ninth and Tenth Streets. That establishment was abandoned and decayed within the next 20 years. In the 1840s the Mormons built a town called Cutler's Park in the area before resuming their westward migration on the Mormon Trail. In 1854 Logan Fontenelle and the Omaha Tribe sold the majority of their tribal land, four million acres (16,000 km²), to the United States for less than 22 cents an acre. This allowed the settlement of Nebraska Territory and the founding of Omaha City. That year the formation of the Territory in the Kansas–Nebraska Act was based on the condition that it remain slave-free. Pioneer Omaha: 1853 to 1867 In 1853 William D. Brown operated the Lone Tree Ferry to shuttle California Gold Rush prospectors and Oregon Trail settlers across the river between Kanesville, Iowa and the Nebraska Territory. The Lone Tree Ferry eventually became the