Which benefit was not provided to New Mexico by the Treaty of Guadalupe-Hidalgo?

The correct answer reflects the notion that the Treaty of Guadalupe-Hidalgo, signed in 1848, had significant implications for the territory now known as New Mexico. While the treaty did promise citizenship to Mexican residents in the ceded territories, this aspect was often poorly enforced; therefore, many Mexicans and their descendants faced challenges in claiming their rights and recognition as U.S. citizens.

The treaty fundamentally ended the Mexican-American War, which is a direct outcome but not a benefit unique to New Mexico alone. It also established the new boundaries for territories, specifically setting the framework for what would become New Mexico and Arizona. Additionally, the treaty facilitated infrastructure developments such as mail routes and post offices, which were essential for connecting the newly acquired territories with the rest of the United States.

Overall, while the promise of citizenship was included in the treaty, the practical realization of that promise was fraught with difficulties, making it less of a guaranteed or fully realized benefit compared to the other significant outcomes linked directly to the treaty's terms.