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.
Pennsylvania is the 33rd-largest, the 6th-most populous, and the 9th-most densely populated of the 50 United States. The state's five most populous cities are Philadelphia (1,560,297), Pittsburgh (305,801), Allentown (118,577), Erie (100,671), and Reading (89,893). The state capital, and its ninth-largest city, is Harrisburg. Pennsylvania has 140 miles (225 km) of shoreline along Lake Erie and the Delaware Estuary.