 After the Louisiana Purchase in 1803, President Thomas Jefferson and his successors viewed much of the land west of the Mississippi River as a place to resettle the Native Americans, so that white settlers would be free to live in the lands east of the river.Indian removal became the official policy of the United States government with the passage of the 1830 Indian Removal Act, formulated by President Andrew Jackson.When Louisiana became a state in 1812, the remaining territory was renamed Missouri Territory to avoid confusion.