Which Modern States Were Once Part of the Republic of Texas?

The Republic of Texas (1836–1845) claimed a vast territory extending far beyond the boundaries of the current state. When Texas joined the Union in 1845 and subsequently ceded its northern and western claims in the Compromise of 1850, parts of its former domain became portions of six present-day U.S. states.

The Six States

1. Texas: The core territory, retaining the bulk of the former republic.
2. Oklahoma: The "Panhandle" (Oklahoma Panhandle / "No Man's Land") was part of Texas's northern claim above the 36°30' parallel (the Missouri Compromise line).
3. Kansas: A small southwestern corner (south of the Arkansas River and west of the 100th meridian) was included in Texas's claim.
4. Colorado: A slice of southeastern Colorado (south of the Arkansas River, east of the Rockies) was claimed by Texas.
5. New Mexico: The entire eastern portion, including the future cities of Santa Fe, Albuquerque, and Las Cruces, was claimed by Texas as far west as the Rio Grande.
6. Wyoming: A tiny triangular sliver in the southeast (south of the 42nd parallel, east of the Continental Divide) fell within Texas's northwestern ambition.

Historical Context

Texas's claims were based on the Treaties of Velasco (1836) with Mexico, which Mexico never ratified. The boundaries were disputed throughout the Republic era. The Compromise of 1850 resolved the dispute: Texas surrendered all claims north of 36°30' and west of the 103rd meridian (and a portion of its claim on New Mexico east of the Rio Grande) in exchange for $10 million in federal assumption of its debt. This established the modern Texas borders.