Attached to the Treaty of Guadalupe Hidalgo, this drawing is the Disturnell Map, also known as, "Mapa de los Estados Unidos de Mejico, segun lo organizado y definido por las varias actas del Congreso de dicha republica : y construido por las mejores autoridades."  The map was designed to establish a "boundary line with due precision, upon authoritative maps, and to establish upon the ground landmarks which shall show the limits of both republics."  It contains several major errors, including the position of the Rio Grande.  Using map data, your position may not be valid.