1a river that rises in the Rocky Mountains of northern Colorado and flows southwest for 1,468 miles (2,333 km) to the Gulf of California. It passes through the Grand Canyon. 2a river that flows east for 900 miles (1,450 km) across Texas, from the Llano Estacado to the Gulf of Mexico. Austin is situated on it. 3a state in the central US; population 4,939,456 (est. 2008); capital, Denver; statehood, Aug. 1, 1876 (38). Part of Colorado was acquired by the US with the Louisiana Purchase in 1803 and the rest was ceded by Mexico in 1848.