Before these laws could be put into effect, a new wave of white settlers swept westward and formed the territories of Wisconsin and Iowa. This made it necessary for the policy makers in Washington to shift the permanent Indian frontier from the Mississippi River to the 95th meridian. (This line ran from Lake of the Woods on what is now the Minnesota-Canada border, slicing southward through what are now the states of Minnesota and Iowa, and then along the western borders of Missouri, Arkansas, and Louisiana, to Galveston Bay, Texas.) To keep the Indians beyond the 95th meridian and to prevent unauthorized white men from crossing it, soldiers were garrisoned in a series of military posts that ran southward from Fort Snelling on the Mississippi River to forts Atkinson and Leavenworth on the Missouri, forts Gibson and Smith on the Arkansas, Fort Towson on the Red, and Fort Jesup in Louisiana.

– Dee Brown

Bury My Heart at Wounded Knee: An Indian History of the American West. The laws referred to were the Act passed by U.S. Congress on June 30, 1844 An Act to Regulate Trade and Intercourse with the Indian Tribes, and to Preserve Peace on the Frontiers.