United States and Territories, 1789-Present–
Territorial Population at Admission
The United States Constitution came into effect, forming the new nation. Note that the states ratified at different times, but to simplify the map, the final result is shown here.
August 7, 1789: The United States Congress affirmed the organization of the Territory North West of the Ohio River, or Northwest Territory, under the terms of the Northwest Ordinance.
April 2, 1790: Congress accepts North Carolina’s cession of its western counties, which had initially been ceded on December 22, 1789. The land became unorganized territory.
May 26, 1790: The Southwest Ordinance organized the Territory South of the Ohio River, or Southwest Territory, which corresponded to present-day Tennessee.
March 4, 1791: The Vermont Republic, which had portions claimed by New York and New Hampshire and, while unrecognized by the United States, was a de facto independent country, was admitted as the 14th state, Vermont.
September 9, 1791: The District of Columbia, the nation’s federal district, was formed from land granted by Maryland and Virginia; the Virginia portion would be returned in 1847.
March 3, 1792: The federal government sold the Erie Triangle to Pennsylvania.
June 1, 1792: The western counties of Virginia beyond the Appalachian Mountains were split off and admitted as the 15th state, Kentucky.
October 27, 1795: Pinckney’s Treaty, also known as the Treaty of San Lorenzo, signed on October 27, 1795, and proclaimed on August 3, 1796, settles the northern border of West Florida as the 31st parallel.
June 1, 1796: The Southwest Territory was admitted as the 16th state, Tennessee.
April 7, 1798: Due to the Yazoo Land Fraud, an act was signed by President John Adams, authorizing him to appoint commissioners to negotiate with Georgia about ceding its western land. The act created Mississippi Territory in the region ceded by West Florida, corresponding to roughly the southern third of present-day Mississippi and Alabama except their panhandles, which were part of West Florida.
July 4, 1800: Indiana Territory was formed from the western portion of Northwest Territory. It corresponded to present-day Illinois, Indiana, northeastern Minnesota, and Wisconsin, as well as the western half of the Lower Peninsula of Michigan and all but the eastern tip of the Upper Peninsula. Northwest Territory was left with only most of Ohio and the rest of Michigan.
July 10, 1800: Connecticut ceded its Western Reserve to the federal government, which made it part of Northwest Territory, and is the northeastern part of present-day Ohio.
April 26, 1802: Georgia finally ceded its western claims, the Yazoo Lands, to the federal government, where it became unorganized land.
March 1, 1803: The southeastern portion of Northwest Territory was admitted as the 17th state, Ohio. The remainder of Northwest Territory was transferred to Indiana Territory.
April 30, 1803: The Louisiana Purchase was made, expanding the United States west of the Mississippi River. There was a dispute with West Florida over how much land east of the Mississippi River it included. West of the Mississippi, it was defined as the Mississippi Basin, whose extent was not known at the time and extends slightly north of the modern Canada-US border. It consisted of the whole of present-day Arkansas, Kansas, Iowa, Missouri, Nebraska, and Oklahoma, and portions of Colorado, Louisiana, Minnesota, Montana, New Mexico, North Dakota, South Dakota, Texas and Wyoming. It also included the southernmost portions of the present-day Canadian provinces of Alberta, Manitoba, and Saskatchewan.
March 27, 1804: The unorganized land ceded by Georgia was added to Mississippi Territory, consisting of the whole of present-day Mississippi and Alabama, minus their panhandles which were still part of West Florida.
October 1, 1804: The Louisiana Purchase was split into the District of Louisiana, which was temporarily under the authority of Indiana Territory, and the organized Territory of Orleans, which corresponded to part of present-day Louisiana with a small portion of Texas. The western border of Orleans Territory caused further conflict with New Spain, specifically over the region between the Sabine River on the west and the Arroyo Hondo (River) on the east, which became known as the Sabine Free State. This land was later confirmed as U.S. territory by the Adams-Onís Treaty of 1819.
January 11, 1805: Michigan Territory was split from Indiana Territory, including the whole of the lower peninsula of present-day Michigan but only that eastern tip of the upper peninsula which was held by the Northwest Territory after Indiana Territory had been split from it.
July 4, 1805: The District of Louisiana was organized as Louisiana Territory.
March 1, 1809: Illinois Territory was split from Indiana Territory. Illinois Territory included present-day Illinois, northeastern Minnesota, and Wisconsin. Indiana Territory included the present-day borders of Indiana, with its western and eastern borders continuing northward; thus, it also included the central portion of the upper peninsula of Michigan, as well as Door Peninsula of present-day Wisconsin.
April 1810: The Hawaiian islands are unified as the Kingdom of Hawaii.
October 27, 1810: By proclamation by President James Madison, the United States annexed the Baton Rouge and Mobile Districts of West Florida, declaring them part of the Louisiana Purchase. These had, 90 days earlier, declared independence as the Republic of West Florida.
April 30, 1812: Most of the Territory of Orleans was admitted as the 18th state, Louisiana. The rest of the territory (the northwestern tip) was ceded to Louisiana Territory.
May 12, 1812: The federal government annexed a part of West Florida, the Mobile District, to Mississippi Territory, making the territory correspond to present-day Alabama and Mississippi.
June 4, 1812: Louisiana Territory, having the same name as a state, was renamed to Missouri Territory.
December 11, 1816: The southern portion of Indiana Territory was admitted as the 19th state, Indiana. The remainder became unorganized.
March 3, 1817 Alabama Territory was split from Mississippi Territory; both correspond to their present-day counterparts.
December 10, 1817: Mississippi Territory was admitted as the 20th state, Mississippi.
October 20, 1818: The Treaty of 1818 established the 49th parallel north west of the Lake of the Woods as the border with British-held lands, and Oregon Country was established as a shared land between the United States and United Kingdom. Oregon Country consisted of most of present-day Idaho and Oregon, all of Washington, and a portion of Montana, as well as the southern part of the Canadian province of British Columbia. The treaty transferred the Red River Basin to the United States, consisting of northwestern Minnesota, northeastern North Dakota, and the northeastern tip of South Dakota.
December 3, 1818: The southern portion of Illinois Territory was admitted as the 21st state, Illinois. The remainder was reassigned to Michigan Territory. The unorganized lands which had been a part of Indiana Territory prior to the admission of Indiana as a state were also assigned to Michigan Territory.
March 2, 1819: The southern part of Missouri Territory was organized as Arkansaw Territory, consisting of present-day Arkansas as well as part of Oklahoma. It was not officially spelled Arkansas until later.
December 14, 1819: Alabama Territory was admitted as the 22nd state, Alabama.
March 16, 1820: The Maine District of Massachusetts was split off and admitted as the 23rd state, Maine, as part of the Missouri Compromise.
July 10, 1821: The Adams-Onís Treaty or Transcontinental Treaty came into effect, establishing a defined border between the United States and New Spain. The treaty ceded Spain’s claims to Oregon Country to the United States and American claims to Texas to Spain; moved portions of present-day Colorado, Oklahoma, and Wyoming, and all of New Mexico and Texas, to New Spain; and all of Spanish Florida to the United States. The new borders intruded on Arkansaw Territory’s Miller County, created on April 1, 1820, which dipped below the Red River and into land now ceded to Spain. However, the remoteness of the region caused no serious conflict with Spain.
August 10, 1821: The southeastern corner of Missouri Territory was admitted as the 24th state, Missouri. The remainder became unorganized. Missouri did not include its northwestern triangle at this point, that being added later in the Platte Purchase.
September 27, 1821: The Viceroyalty of New Spain achieved independence as Mexico. Spanish Texas became Mexican Texas. | March 30, 1822: East Florida and the portion of West Florida not already part of other states were combined and organized as Florida Territory, which corresponded to present-day Florida. Around this time, the official spelling of Arkansaw Territory became Arkansas Territory.
November 15, 1824: Arkansas Territory was shrunk, the western portion becoming unorganized.
May 6, 1828: Arkansas Territory was shrunk further, attaining the present-day borders of Arkansas, with the remainder again becoming unorganized, excepting the land it still claimed as Miller County.
June 30, 1834: A large portion of unorganized land was added to Michigan Territory, corresponding to present-day Iowa, western Minnesota, and eastern North Dakota and South Dakota.
March 2, 1836: The Republic of Texas achieved independence from Mexico, though with a large portion of the territory disputed. It had control over the eastern half of present-day Texas, and disputed the western half, as well as portions of Colorado, Kansas, New Mexico, and Wyoming. Miller County in Arkansas Territory now intruded on the borders of Texas, and the people there began to take a Texian identity, leading to both governments having representatives from the county.
June 15, 1836: Arkansas Territory was admitted as the 25th state, Arkansas. It continued to claim Miller County, with increasing irrelevance.
July 4, 1836: Wisconsin Territory was split off from Michigan Territory, consisting of present-day Wisconsin, Minnesota, Iowa, and eastern North and South Dakota. As an inducement to give up its claim over the Toledo Strip to Ohio, the whole of the present-day upper peninsula was assigned to Michigan Territory, giving it the present-day borders of Michigan.
January 26, 1837: Michigan Territory was admitted as the 26th state, Michigan.
March 28, 1837: The Platte Purchase added a small area of land to Missouri, giving it its present-day boundaries.
July 4, 1838: Iowa Territory was split off from Wisconsin Territory, consisting of present-day Iowa, western Minnesota, and eastern North Dakota and South Dakota, leaving Wisconsin Territory with northeastern Minnesota and Wisconsin.
November 10, 1842: The Webster-Ashburton Treaty settled the border between the United States and lands held by the United Kingdom east of the Rocky Mountains, ending the disputes over the northern border of the state of Maine and northeastern border of Wisconsin Territory, which today resides in present day Minnesota.
March 3, 1845: Florida Territory was admitted as the 27th state, Florida.
December 29, 1845: The Republic of Texas was admitted as the 28th state, Texas. The United States Congress passed the joint resolution of annexation on March 1, 1845, but Texas did not agree to join the union for some time after. Although the annexation resolution avoided specifying Texas’s boundaries, the U.S. inherited Texas’s unenforced claims to South Texas, West Texas, over half of New Mexico, a third of Colorado, and small parts of Oklahoma, Kansas and Wyoming. With Texas joining the union, Arkansas finally gave up its claim on Miller County.
June 18, 1846: The Oregon Treaty established the 49th parallel west of the Lake of the Woods as the continental border (so it did not include Vancouver Island) with the lands held by the United Kingdom. The sharing of Oregon Country ended, and the American portion becomes unorganized territory.
December 28, 1846: The southeast portion of Iowa Territory was admitted as the 29th state, Iowa. The remainder became unorganized.
February 2, 1848: The Treaty of Guadalupe Hidalgo ended the Mexican-American War. Mexico ceded the Texas-claimed areas as well as a large area of land consisting of all of present-day California, Nevada, and Utah, most of Arizona, and portions of Colorado, New Mexico, and Wyoming.
May 29, 1848: The southeastern portion of Wisconsin Territory was admitted as the 30th state, Wisconsin. The remainder became unorganized.
August 14, 1848: Oregon Territory was organized, including present-day Idaho, northwestern Montana, Oregon, Washington, and western Wyoming.
March 3, 1849: Minnesota Territory was organized, consisting of present-day Minnesota, and eastern portions of North Dakota and South Dakota.
September 9, 1850: The Compromise of 1850 divided the Mexican Cession and land claimed by Texas but ceded to the federal government in exchange for taking on its debts. The western portion was admitted as the 31st state, California, most of the rest was organized as Utah Territory and New Mexico Territory, and a small portion became unorganized land. New Mexico Territory consisted of most of present-day Arizona and New Mexico, as well as a southern portion of Colorado and the southern tip of Nevada. Utah Territory consisted of present-day Utah, most of Nevada, and portions of Colorado and Wyoming.
March 2, 1853: Washington Territory was split from Oregon Territory, consisting of present-day Washington, northern Idaho, and the western tip of Montana, leaving Oregon Territory with all of Oregon, southern Idaho and a portion of Wyoming.
December 30, 1853: The Gadsden Purchase added some land to New Mexico Territory, corresponding to the southernmost areas of present-day Arizona and New Mexico.
May 30, 1854: Kansas Territory and Nebraska Territory were organized; the remaining unorganized land colloquially became known as Indian Territory. Kansas Territory consisted of present-day Kansas and eastern Colorado. Nebraska Territory consisted of present-day Nebraska, and parts of Colorado, Montana, North Dakota, South Dakota, and Wyoming. Indian Territory corresponds to eastern Oklahoma. A peculiarity appeared at this time, when a small strip of land north of Texas was not officially assigned by any state or territory; this came to be called the Neutral Strip or “No Man’s Land”, which corresponds to the present-day panhandle of Oklahoma.
May 11, 1858: The eastern portion of Minnesota Territory was admitted as the 32nd state, Minnesota. The remainder became unorganized.
February 14, 1859: The western portion of Oregon Territory was admitted as the 33rd state, Oregon. The remainder was assigned to Washington Territory.
February 8, 1860: Texas began claiming Greer County, Texas, controlled at that time by the federal government as unorganized territory, and now in present-day Oklahoma.
January 29, 1861: The eastern portion of Kansas Territory was admitted as the 34th state, Kansas. A peculiarity arose for the western portion. It was added to Colorado Territory on February 28, 1861; however, for the month between statehood for Kansas and the Colorado Territory being formed, it appears to have had no official status.
February 4, 1861: The Confederate States of America (CSA) was formed. The Southern states seceded at different dates and joined the CSA at different dates; to simplify the map, only the final form of the CSA is shown here. There were rebel governments as well as Union governments in Kentucky and Missouri, and the CSA had full control over Indian Territory.
February 28, 1861: Colorado Territory was organized, with land from Utah, New Mexico, and Nebraska Territories, as well as the land left over from Kansas Territory; it corresponded already to present-day Colorado. Also, the eastern tip of Washington Territory was transferred to Nebraska Territory.
March 2, 1861: Dakota Territory was split from Nebraska Territory, and included the unorganized land left over from Minnesota Territory. Dakota Territory consisted of both present-day North and South Dakota, as well as most of Montana and northern Wyoming. Nebraska Territory consisted of all of Nebraska and southeastern Wyoming. Nevada Territory was split from Utah Territory, corresponding to northwestern present-day Nevada; the eastern border was the 39th meridian west of Washington, D.C.
August 1, 1861: The Confederacy established Arizona Territory (CSA) in the southern half of the Union’s New Mexico Territory. It would be organized on February 14, 1862. It corresponded to the southern halves of present-day Arizona and New Mexico.
July 14, 1862: Due to its nature as a mining and grazing area, land started to be added to Nevada Territory to accommodate these activities. Its eastern border was moved eastward from the 39th meridian west from Washington, to the 38th meridian west from Washington, transferring the land from Utah Territory.
February 24, 1863: The Union created its own Arizona Territory, splitting it off from New Mexico Territory, making both territories correspond to their present-day states, except for Arizona Territory including the southern tip of present-day Nevada.
March 4, 1863: Idaho Territory was created from portions of Washington, Dakota, and Nebraska Territories, consisting of present-day Idaho, Montana, and most of Wyoming. Nebraska and Washington Territories were left corresponding to their present-day counterparts.
June 20, 1863: Several counties of northwestern Virginia who didn’t want to be part of the Confederacy split off and were admitted as the 35th state, West Virginia
May 26, 1864: Montana Territory was split from Idaho Territory, which also had some land transferred to Dakota Territory. Montana Territory corresponded to present-day Montana, Idaho Territory consisted of Idaho and western Wyoming, and Dakota Territory included both North and South Dakota, and most of Wyoming.
October 31, 1864: Nevada Territory was admitted as the 36th state, Nevada; it was a bit smaller than it is today, lacking area in both the east and south.
April 9, 1865: The Confederate States of America surrendered. The process of Reconstruction and readmission to the union would take several years; to simplify the map, they are shown as already readmitted.
May 5, 1866: Nevada’s eastern border was moved from the 38th meridian west from Washington, to the 37th meridian west from Washington, transferring land to it from Utah Territory.
January 18, 1867: The northwestern corner of Arizona Territory was transferred to the state of Nevada, giving it its present-day borders.
March 1, 1867: Nebraska Territory was admitted as the 37th state, Nebraska.
October 11, 1867: The United States purchased Alaska from Russia; it was designated the Department of Alaska, and corresponds, except for a boundary dispute, to present-day Alaska.
July 25, 1868: Wyoming Territory was formed from portions of Dakota, Idaho, and Utah Territories, corresponding to the present-day borders of Wyoming.
August 1, 1876: Colorado Territory was admitted as the 38th state, Colorado.
May 17, 1884: The Department of Alaska, previously under the direct control of the federal government and the military, was redesignated the District of Alaska, forming a local government.
November 2, 1889: Dakota Territory was split in two, and it was admitted as the 39th state, North Dakota, and 40th state, South Dakota.
November 8, 1889: Montana Territory was admitted as the 41st state, Montana.
November 11, 1889: Washington Territory was admitted as the 42nd state, Washington.
May 2, 1890: Oklahoma Territory was organized from the western portion of Indian Territory, and included the Neutral Strip, and corresponded to the western half of present-day Oklahoma.
July 3, 1890: Idaho Territory was admitted as the 43rd state, Idaho.
July 10, 1890: Wyoming Territory was admitted as the 44th state, Wyoming. | July 4, 1894: The Kingdom of Hawaii became the Republic of Hawaii.
January 4, 1896: Utah Territory was admitted as the 45th state, Utah.
May 4, 1896: A Supreme Court ruling officially assigns Greer County to Oklahoma Territory.
August 12, 1898: The Republic of Hawaii was annexed by the United States. | June 14, 1900: The annexed Hawaiian islands were organized as the Territory of Hawaii, and corresponded, except for including Palmyra Atoll, to the present-day state of Hawaii.
November 16, 1907: Oklahoma Territory and Indian Territory were combined and admitted as the 46th state, Oklahoma.
January 6, 1912: New Mexico Territory was admitted as the 47th state, New Mexico.
February 14, 1912: Arizona Territory was admitted as the 48th state, Arizona.
August 24, 1912: The District of Alaska was organized as Alaska Territory.
January 3, 1959: Alaska Territory was admitted as the 49th state, Alaska.
August 21, 1959: Hawaii Territory was admitted as the 50th state, Hawaii, resulting in the present-day situation of the United States. The statehood act specifically excluded Palmyra Atoll from the new state; it thus became unorganized land. Since it had been incorporated as part of the Hawaii Territory, Palmyra Atoll became the only incorporated territory left in the United States.