The state was named for the Colorado River, which Spanish travelers named the Río Colorado for the ruddy (Spanish: colorado) silt the river carried from the mountains. The Territory of Colorado was organized on February 28, 1861, and on August 1, 1876, U.S. President Ulysses S. Grant signed Proclamation 230 admitting Colorado to the Union as the 38th state. Colorado is nicknamed the "Centennial State" because it became a state a century after the signing of the United States Declaration of Independence.
The state has a wide range of elevations, from sea level on the coast to 6,684 feet (2,037 m) at Mount Mitchell, the highest point in North America east of the Mississippi River. The climate of the coastal plains is strongly influenced by the Atlantic Ocean. Most of the state falls in the humid subtropical climate zone. More than 300 miles (500 km) from the coast, the western, mountainous part of the state has a subtropical highland climate.