Note I'-31 — Chapter I · ITINERARY: THROUGH NEW MEXICO ON THE RIO GRANDE TO EL PASO, FEB. 27TH-MAR. 21ST, 1807.

In the vicinity of Montoyo, Tex., in the extreme W. corner of the State. Passing successively Mesquite, Herron, and Lyndon, on the railroad, with San Miguel (Baca Grant), La Mesa, and Chamberino in succession on the other side of the river, Pike comes to the station Anthony and the parallel of 32° N.; on crossing which he goes from Dona Ana Co., N. M., into El Paso Co., Tex., as he proceeds down the left or E. bank of the river; had he been on the other side he would have remained in New Mexico until he entered present Chihuahua at lat. 31° 47´ N. For the course of the Rio Grande itself makes the irregular boundary of Texas for 15 or 20 m., from the point where the parallel of 32° N. strikes the river from the E., to that where the parallel of 31° 47´ N. leaves the river on the W. This break or fault (as a miner would say of a lead that acted so) of the straight border between Texas and New Mexico, where the boundary slips 13´ S. down the Rio Grande, is one of the politico-geographical curiosities of the situation, which would only be fully understood upon mastering the complicated history of the U. S. and Mexican Boundary Survey in all the bitterness of its personal episodes. Some of these points are considered in the following note. From lat. 31° 47´ N. on the Rio Grande, in the immediate vicinity of El Paso, Tex., and of El Paso del Norte (Ciudad Juarez), in Chihuahua, the river forms the boundary between the United States and the Republic of Mexico—that is, between Texas and the Mexican States of Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas—on a circuitous but in general S. E. course to the Gulf of Mexico.