What was the border argument between Mexico and US about?

The border argument between Mexico and the United States has a long and complex history, dating back to the mid-19th century. The primary point of contention revolves around the territory that was acquired by the United States following the Mexican-American War. Mexico ceded roughly half of its territory to the United States in the Treaty of Guadalupe Hidalgo, including the present-day states of California, Nevada, Utah, Arizona, New Mexico, and parts of Colorado and Wyoming.

The disagreement arises from disputes over the precise location of the boundary line established by the treaty. Several regions along the border have been contested, notably in areas where rivers change course or geographical features shift due to natural processes. The Rio Grande (known as the Rio Bravo in Mexico) has frequently been a source of disagreement due to its shifting course.

Furthermore, issues concerning water rights, drug trafficking, immigration, and the construction of barriers along the border have further strained relations between the two countries. In recent years, tensions have escalated due to the United States' implementation of stricter immigration policies and the construction of sections of a physical barrier along certain parts of the border.

Both nations have engaged in extensive diplomatic efforts, negotiations, and international commissions to resolve the border disputes. While significant progress has been made in demarcating and maintaining much of the border, certain contested areas still remain as potential points of tension between Mexico and the United States.