New Mexico v. Texas

Background

The States of New Mexico and Texas disputed their common boundary in the Rio Grande valley between the 32° north parallel and the international boundary at 31°47'. The case was heard on the pleadings and the special master’s report. The Court considered an opinion announced December 5, 1927, modified it in certain respects, and addressed exceptions to the master’s report filed by both States. The Court overruled New Mexico’s exceptions, sustained Texas’s exceptions, dismissed New Mexico’s bill, and sustained Texas’s cross-bill.

Reasoning

The core question was where the true state line lies along this stretch of the Rio Grande. The Court adopted the special master’s boundary description: the boundary is the middle of the river channel as it existed on September 9, 1850, as outlined in Section V(1) of the master’s report. The Court also adopted the master’s measured reference points, including taking the east-bank intersection with the 32nd parallel 600 feet west of Clark Monument No. 1 and a middle line located 150 feet from the east and west banks, respectively. To implement the decree, the Court appointed Samuel S. Gannett as commissioner to run, locate, and mark the boundary, using the most accurate scientific methods, establishing permanent monuments, and filing maps, field notes, and a formal report.

Real world impact

The ruling fixes the official state boundary between New Mexico and Texas along the specified Rio Grande channel as of 1850 and directs a formal survey and marking. The commissioner must take an oath, report his methods and costs, and the work is subject to Court approval. Copies of the commissioner’s report will be sent to both Governors, objections must be filed within forty days, and remaining costs are split equally by the two States.