^ abThe Muddy Creek post office closed on November 19, 1886, but reopened as Abbey on May 29, 1891.
^On November 20, 1882, the Hillerton, Colorado post office was moved to Abbeyville.
^ abThe San Isidro post office closed in 1902, but was reopened for one day as Abeyta in 1914.
^ abOn September 10, 1885, the name of the Bush post office was changed to Adams.
^On October 11, 1963, the Adams City post office became a branch of the Commerce Town post office.
^ abOn April 24, 1882, the Gebhard post office was renamed Agate.
^On August 31, 1955, the Airport, Colorado post office was made a rural station of Pueblo, Colorado.
^ abThe Alamo, Colorado post office was renamed Butte Valley on October 1, 1938.
^ abThe Berkeley post office was renamed Alcott in 1896.
^ abcThe Oxford post office was renamed Fowler in 1890, and was then renamed Alexander in 1900, but was then changed back to Fowler later that year.
^Located at an elevation of 10,361 feet (3,158 m), the Alma, Colorado post office has been the highest elevation U.S. post office since January 4, 1974.
^On September 18, 1888, the Alva post office was renamed Idalia.
^ abThe Amethyst post office was renamed Creede on February 2, 1909.
^ abThe Animas City post office closed on August 19, 1885, but reopened as the Animas post office on July 10, 1886.
^Located at an elevation of 11,185 feet (3,409 m), the Animas Forks, Colorado Territory post office was the highest elevation U.S. post office from its opening on February 8, 1875, until February 10, 1876, and again from September 24 to October 16, 1879. Colorado joined the Union on August 1, 1876.
^ abThe name of the San Antonito post office was changed to Antonito on January 24, 1881.
^In operation from June 15, 1895, until March 31, 1919, the Arastra, Colorado post office was the highest elevation U.S. post office ever at an elevation of 12,230 feet (3,728 m).
^ abThe Arbourville post office was renamed Conrow in 1881.
^ abThe Argenta, Colorado post office was renamed Tomichi on August 23, 1880.
^ abThe Conger post office was renamed Argentine in 1881.
^ abcThe Decatur post office closed in 1885, but reopened as Rathbone in 1891. The Rathbone Post Office closed in 1895, but reopened as Argentine in 1901.
^ abcdThe Auroria post office was moved to Colona on April 27, 1860. The Colona Post Office closed on February 11, 1861, but reopened on July 15, 1860 as La Porte. The La Porte post office closed on December 12, 1864 but reopened on October 5, 1866. The name of the La Porte post office was changed to Laporte on December 21, 1894. La Porte was the original seat of Heele County, Jefferson Territory and then Larimer County, Colorado Territory.
^ abThe Aylmer post office was renamed Bowen on September 18, 1906.
^ abThe spelling of the Bijouview post office was changed to Bijou View on June 10, 1921.
^ abcThe name of the Black Hawk Point post office was shortened to Black Hawk on February 8, 1871, was then respelled Blackhawk on January 30, 1895, but was then changed back to Black Hawk on July 1, 1950.
^ abThe Devine post office was renamed Black Mountain in 1899.
^ abBreckenridge was founded in 1859 and named for prospector Thomas Breckenridge. In 1860, the town changed the spelling of its name to Breckinridge in honor of U.S. Vice PresidentJohn Cabell Breckinridge. On December 2, 1861, thirty days after John Breckinridge accepted a commission as a brigadier general in the Confederate States Army, the loyal Union town changed its name back to the original Breckenridge.
^Located at an elevation of 9,728 feet (2,965 m), the Breckinridge, Utah Territory post office was the highest elevation U.S. post office from its opening on January 18, 1860, until February 16, 1861.
^ abThe Brown post office was renamed Olathe on June 04, 1896.
^ abcThe Kraft post office was renamed Brown's Cañon on May 8, 1888. The Brown's Cañon post office closed on July 25, 1893, but reopened as Brown Cañon post office on March 9, 1904.
^ abThe Buckley post office was renamed Lycan on June 27, 1913.
^ abLocated at an elevation of 10,761 feet (3,280 m), the Laurette, Colorado Territory post office was the highest elevation U.S. post office from its opening on Nov 14, 1861 until its closing on January 24, 1873. The Laurette post office was renamed Buckskin on December 21, 1865.
^ abThe spelling of the Cañon City post office was changed to Canon City in 1904, but was then changed back to Cañon City in 1994.
^ abThe Scissors post office was renamed Capps in 1894.
^ abThe Corrizo post office was renamed Carrizo in 1907.
^Located at an elevation of 11,574 feet (3,528 m), the Carson, Colorado post office was the highest elevation U.S. post office from its opening on September 16, 1889, until June 15, 1895.
^ abThe Castle post office was renamed Eagle in 1891.
^ abThe first Castle Rock post office was renamed Douglas in 1874.
^ abThe first Julesburg post office moved to Clearwater in 1862.
^ abThe Clemmons post office closed in 1898, but reopened as Schley the following year.
^ abThe Cliff post office was renamed Cliffdale in 1923.
^Located at an elevation of 11,342 feet (3,457 m), the Climax, Colorado post office was the highest elevation U.S. post office from March 31, 1919, until its final closing on January 7, 1974.
^ abThe Clonmell post office was renamed Cramer in 1901.
^ abThe Seward post office was renamed Clyde in 1899.
^ abThe spelling of the Coal Creek post office was changed to Coalcreek in 1894, but was then changed back to Coal Creek in 1964.
^ abcThe Conger post office was renamed Pallas in 1895, and was then renamed Huggins in 1906. The Huggins Post Office closed in 1908, but reopened as Pallas in 1912.
^ abThe Coryell post office was renamed Stanley in 1890.
^On November 1, 1861, the Territory of Colorado created 17 original counties, with San Miguel as the original seat of Costilla County, Colorado Territory. When its post office opened on November 13, 1862, the village selected the new name Costilla, perhaps in recognition of its new status.[1] In 1863, county voters decided to move the county seat 17 miles (27 km) north to San Luis. In 1869, a U.S. government survey determined that Costilla was actually located in Taos County, New Mexico Territory.[8] It wasn't until October 21, 1872, that the village post office was officially renamed Costilla, New Mexico Territory.[1]
^ abThe Cotton Creek post office was renamed Mirage in 1895.
^ abcThe Windsor post office closed in 1880, but reopened as Yampa in 1883, and was then renamed Craig in 1889.
^ abcThe Willow post office was renamed Creede on July 1, 1891. The post office was moved to North Creede on November 28, 1908.
^ abThe Crosson post office closed in 1885, but reopened as Crossons in 1920.
^ abcThe Vermilion post office was renamed Resort in 1880. The Resort Post Office closed in 1886, but reopened as Dawson in 1890.
^ abThe spelling of the De Beque post office was changed to Debeque in 1894, but was then changed back to De Beque in 1902.
^ abThe Dillingham post office was renamed De Nova in 1916.
^ abcThe Deane post office closed in 1884, but reopened as Deansbury in 1890. The Deansbury Post Office closed in 1892, but reopened as Strontia Springs in 1911.
^ abThe spelling of the Deer Trail post office was changed to Deertrail in 1894, but was then changed back to Deer Trail in 1950.
^ abThe Delphi post office was renamed Wallstreet in 1898.
^ abThe name of the Denver City post office was shortened to Denver on February 13, 1866.
^ abcThe second Julesburg post office was renamed Denver Junction in 1885. The Denver Junction Post Office closed the following year, but reopened as Weir in 1889.
^ abThe Sheffield post office was renamed Denver Mills in 1892.
^ abcThe Washburn post office was renamed Derblay in 1892, but was then changed back to Washburn the same year, only to be renamed Hazeltine the following year.
^ abThe Disappointment post office closed in 1920, but reopened as Willow Gulch the following year.
^ abcdThe Divide post office was renamed Dolomite in 1886, then renamed Higgins in 1890, then renamed Newett in 1895.
^ abThe Dodsonville post office was renamed Linwood in 1876.
^ abThe Dora post office was renamed Gove in 1883.
^ abcThe Horse Shoe post office closed in 1886, but reopened as Horseshoe in 1890. The Horseshoe Post Office closed in 1894, but reopened as Doran in 1901.
^ abThe Doyleville post office was renamed Gilman in 1882, but was then changed back to Doyleville the following year.
^ abThe Hibbard post office was renamed Drennan in 1922.
^ abcIn 1869, the Fort Lupton post office was moved one mile (1.6 km) south from the stage stop to the settlement and the old post office was renamed Weld.
^ abThe spelling of the Highlandlake post office was changed to Highland Lake in 1910.
^ abThe Highlandtown post office was renamed Highlands in 1884.
^ abThe spelling of the Hill Top post office was changed to Hilltop in 1896.
^ abThe spelling of the Hillsborough post office was changed to Hillsboro in 1891,
^Located at an elevation of 11,428 feet (3,483 m), the Holy Cross, Colorado post office was the highest elevation U.S. post office from November 10, 1883, to September 16, 1889.
^ abSince their GNIS elevations only differ by 3 feet (0.9 m), both Rexford, Colorado and Holy Cross, Colorado had legitimate claims to the highest elevation U.S. post office from January 23, 1882, to November 10, 1883.
^ abThe Hope post office was renamed Snowden in 1890.
^ abThe name of the Hot Sulphur Springs post office was shortened to Sulphur Springs in 1894, but was then changed back to Hot Sulphur Springs in 1912.
^ abThe Macon post office was renamed Independence in 1899.
^ abcThe Jefferson post office was renamed Morrison in 1873, and was then renamed Mount Morrison in 1908, but was then changed back to Morrison in 1950.
^ abThe Jennison post office was renamed Timber Hill in 1879.
^ abThe Josie post office was renamed Naomi in 1883.
^ abThe Juniper post office was renamed Juniper Springs in 1919.
^ abcThe Radiant post office was renamed Pyrolite in 1915, and was then renamed Kenwood in 1926.
^ abThe Orr post office was renamed Kersey in 1894.
^The Keystone Ranch post office closed in 1865, but reopened as Keystone in 1869.
^ abThe Stevens post office was renamed Kezar in 1882.
^ abThe Kremmling post office was renamed Kinsey in 1891, but was then changed back to Kremmling in 1895.
^ abcThe Los Sauses post office closed on February 15, 1883, but reopened as La Sauses on June 25, 1890. The spelling was then changed to Lasauses on February 28, 1895.
^Located at an elevation of 10,708 feet (3,264 m), the Oro City, Jefferson Territory post office was the highest elevation U.S. post office from its opening on February 16, 1861, until November 14 that year, and again from January 24, 1873, until February 8, 1875. The Territory of Colorado was organized on February 28, 1861.
^ abThe spelling of the Red Cliff post office was changed to Redcliff in 1895, but was then changed back to Red Cliff in 1979.
^Located at an elevation of 11,431 feet (3,484 m), the Rexford, Colorado post office was the highest elevation U.S. post office from its opening on January 9, 1882, until its closing on November 10, 1883.
^ abThe spelling of the Roan post office was changed to Rhone in 1894.
^ abThe spelling of the Rioblanco post office was changed to Rio Blanco in 1950.
^ abThe Rockland post office was renamed Solar in 1915.
^ abThe Rockville post office closed in 1878, but reopened as Rowena in 1894.
^The name "Saguache" is pronounced /səˈwætʃ/. This name comes from the Ute language noun "sawup" /səˈwʌp/ meaning "sand dunes". The Spanish language version of this name is usually spelled "Saguache", while the English language version is usually spelled "Sawatch".
^ abThe Summit, Colorado Territory post office was the highest elevation U.S. post office from its opening on February 10, 1876, until its closing on September 24, 1879, and again from its reopening on October 16, 1879, until January 9, 1882. Colorado was admitted to the Union on August 1, 1876, and the Summit post office was renamed Summitville on November 17, 1880.
^ abcThe Virginia post office was renamed Tin Cup in 1880, and the spelling changed to Tincup in 1895.
^ abcThe Walsenburgh post office was renamed Tourist in 1887, but was then changed back to Walsenburgh after a few weeks. The spelling was changed to Walsenburg in 1892.
^ abThe Tourtellotte post office was renamed Tourtellotte Park in 1894.
