DENVER, Colorado — The United States acquired the eastern part of Colorado in the Lousiana Purchase, but the rest wasn't for sale. Instead, it joined the nation by way of war.
The United States was immersed in the Mexican-American War from April 1846 to February 1848.
Public Historian for History Colorado, Sam Bock, described the war as "a land grab." President James K. Polk saw an opportunity to expand U.S. territory when Texas claimed its own independence and lobbied to become part of the young nation.
"It was a very short, very one-sided war where American troops really won the majority of victories," Bock said. "By 1848, we had troops in Mexico occupying Mexico City."
On Feb. 2, 1848, Mexico signed The Treaty of Guadalupe Hidalgo, "so that the United States didn't annex the entire country and make it part of the U.S.," Bock said.
Instead, Polk settled for taking much of what was then northern Mexico. The treaty changed the borders of the U.S. making a big chunk of Colorado part of the United States.
It meant one day people living in this region were Mexicans and the next, they were Americans.
"It's a refrain you hear a lot," Bock said. "We didn't cross the border. The border crossed us."
People living in the San Louis Valley had one year to decide whether they would become American citizens or move south to continue as citizens of Mexico.
"Particularly in southern Colorado, Trinidad, Pueblo, in the San Louis Valley, the Mexican culture and Mexican traditions are still really strong," Bock said. "I call them Mexican but they don’t really call themselves that. They don’t consider themselves Mexican because they haven’t been for so long."
While the United States acquired the territory that we now know as Colorado through the Treaty of Guadalupe Hidalgo, it wasn't until 1876 that the land officially became a state.
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