The refurbished Thomas J. Lee monument in New Albin, Iowa, seen looking northwesterly into Minnesota. The monument, originally erected by Lee and the U.S. Topographic Engineer Corps in 1849, marks the Minnesota–Iowa boundary near Minnesota's southeast corner. Photographed by William Lass on November 3, 2009.

Tri-State marker at the junction of the states of Minnesota, Iowa, and South Dakota, looking north. The marker was originally erected in 1859. Photographed by William Lass on June 29, 2009.

Map of interstate boundaries in Lake Superior ultimately fixed in 1947.

Map of Minnesota's western boundary south of Lake Traverse.

Map showing three Minnesota–Wisconsin boundaries proposed during the late 1840s. Created by Alan Ominsky and reproduced in Lass, William E., "Minnesota's Separation from Wisconsin," Minnesota History 50 (Winter 1987): 311.

Map of three northern boundaries proposed for the state of Minnesota at varying degrees of latitude.

Map of the boundaries of Iowa approved by Congress in 1845 but rejected by Iowa voters.

Map of the boundaries of Iowa proposed by the Iowa Constitutional Convention of 1844.

Map of North America drawn by John Mitchell, 1755.