Answer:
When the United States Congress voted in 1845 to annex Texas as the 28th state, Mexico broke off diplomatic relations with America.
Explanation:
In 1845, the United States of America annexed the Republic of Texas and recognized Texas as the 28th state of the nation. Thus, the United States inherited the territorial dispute between Texas and Mexico.
Mexico broke diplomatic relations with the US in 1845 on the issue, which eventually led to the Mexican-American War of the following year. The Treaty of Guadalupe Hidalgo ended the war when the United States ratified the treaty on March 10, 1848. The treaty allowed the United States to buy California and other regions of Mexico, on the condition that Americans would have to honor the culture and Mexican values. The annexation of Texas was highly controversial among states and contributed to the increased American regionalism that led to the Civil War.
