The Texas-New Mexico Border: New Mexico Stakes its Claim

In May 1850, at the urging of the Taylor administration, New Mexico held a constitutional convention that drafted a proposed state constitution and petitioned for admission.

The boundary section [of the proposed constitution] . . . prescribed a line beginning at the dam in the Rio Grande near El Paso running due east to 100 degrees west longitude and due north on that meridian to its intersection with the Arkansas River [in what is now Kansas]; then up that river to its source [in what is now Colorado] and then in a direct line to the intersection of 111 degrees west longitude with the Colorado River; then due south on that meridien to the Gila River and up that river to some point yet to be determined as the international boundary by a U.S.-Mexican commission, then east along this international boundary line, to the Rio Grande and, finally, down the Rio Grande to the place of beginning.

Mark J. Stegmaier archly observes:

Just as Texas had laid claim to the settled parts of New Mexico, so did the New Mexico convention audaciously lay claim to an area that included at least two longitudinal degrees of territory within the settled area of Texas.