 After Sullivan died in 1830, the Sullivan Line was extended in the west to the Missouri River in 1836 as the U.S. government in the Platte Purchase bought all the land west from the Indian Boundary Line and then permitted Missouri to annex the land.As part of the purchase, Missouri wanted the Sullivan Line resurveyed.Joseph C. Brown who was involved with establishing the Fifth Principal Meridian from which most of land in the Louisiana Territory was mapped was hired by Missouri to resurvey the land.