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.
North Dakota weathered the Great Recession of the early 21st century with a boom in natural resources, particularly a boom in oil extraction from the Bakken formation, which lies beneath the northwestern part of the state. The development drove strong job and population growth, and low unemployment. However, falling oil prices have put pressure on state finances, leading to questions about the lack of diversity in the North Dakota economy and its vulnerability to commodity price swings.