Final answer:
The impact of sharing a border with Mexico is a study of U.S.-Mexico Relations, which includes trade, immigration, and cultural integration.
Step-by-step explanation:
The impact that sharing a border with Mexico has had on the United States is a study of U.S.-Mexico Relations. The proximity of the two countries and the flow of people, goods, and services across the border have had significant implications for both nations. For example, the United States is the largest foreign purchaser of goods and services from Mexico, which affects the trade balance and the price level in Mexico. In addition, the issue of immigration from Mexico to the United States has sparked debates and policies related to border security, labor market dynamics, and cultural integration.