Texas Annexation

What it is

Texas annexation refers to the incorporation of the Republic of Texas into the United States through a joint resolution of Congress, completed when Texas became the 28th state. The process began under President John Tyler and was finished when James K. Polk, who had campaigned on annexing Texas, signed the final bill on December 29, 1845.

Why it matters

Annexation had been delayed for years because Texas was a large slaveholding territory and because it risked war with Mexico, which did not recognize Texas's independence. Polk's election on an expansionist platform broke the political deadlock, and the annexation directly led to the Mexican-American War in 1846. The map shown here illustrates the disputed territory and borders at the center of this conflict.

Look closer

• Why did the annexation of Texas take almost a decade to complete?
• What does the map's depiction of borders and claimed territory suggest about the roots of the conflict with Mexico?
• How did slavery shape the political debate over annexation?