State cessions

The cession of these lands, which for the most part lay between the Appalachian Mountains and the Mississippi River, was key to establishing a harmonious union among the former British colonies.

By the time of the American Revolution, the boundaries between the Thirteen Colonies that became the United States had been for the most part surveyed and agreed upon.

Their land claims also corresponded in varying degrees to the actual reality on the ground in the west at the eve of the Revolution.

One problem was obvious: in many cases more than one state laid claim to the same piece of territory, but clearly only one would be ultimately recognized as the sovereign.

Virginia in particular, which already encompassed 1 in 5 inhabitants of the new nation, laid claim to modern-day Kentucky, and the vast territory it called Illinois County, and the smaller states feared that it would come to completely dominate the union.

When Georgia finally sold the land west of its current boundaries to the United States for cash in 1802, the last phase of western cessions was complete.

Before the Republic of Texas joined the United States in 1845, it claimed a good deal of land that had never been under the de facto control of the Texan government – Texan attempts to exercise control of these territories as a sovereign state (most famously, the Santa Fe expedition) had ended in disaster.

This was one of the causes of the Mexican–American War of 1846–47 (another being the western land aspirations of the U.S. coupled with the refusal by the United Mexican States to sell its territory to the U.S.).