After Independence, the Constitution of 1824, divided Mexico into states, with the area around Mexico City separated as a Federal District. However, the Tlalpan area was initially part of the then very large State of Mexico, which surrounded Mexico City. Tlalpan became the capital of the State of Mexico from 1837 until 1855, when the area was incorporated into the Federal District. U.S. troops passed this way in 1847 on the road to Coyoacán where they fought Mexican troops at the Battle of Churubusco .