The disputed results that led Congress to declare war with Mexico on May 13, 1846 involved which of the following?

• A. Diplomatic negotiations over tariffs
• B. Combat skirmishes with American and Mexican troops over the Texas southwestern boundary
• C. Economic sanctions against Mexico
• D. Territorial cession disputes

Answer: (C)

The key idea is that the push toward war came from direct armed conflict and a disputed border, not from economic measures. After Texas joined the United States, the boundary with Mexican territory was hotly contested, with Mexican forces clashing with American troops along the frontier in the Rio Grande/Nueces area. When these combat skirmishes occurred on what the U.S. considered American soil, President Polk argued that Mexico had invaded, and Congress moved to declare war in response. Economic sanctions or diplomatic disputes over tariffs weren’t what sparked the declaration, and while disputes over land and boundaries framed the war, the immediate trigger was the on‑the‑ground fighting along the Texas frontier.