<Table> <Tr> <Th> Date </Th> <Th> Event </Th> <Th> Change Map </Th> </Tr> <Tr> <Th> December 29 , 1845 </Th> <Td> The Republic of Texas was annexed and admitted as the twenty - eighth state , Texas . Texas brought with it a substantial territorial dispute with Mexico . While many sources state that Mexico recognized the independence of the eastern portion of Texas , the treaties were rejected by the Mexican government . Texas formally handed over sovereignty to the United States in a ceremony on February 19 , 1846 . The annexation led to the beginning of the Mexican -- American War a few months later . </Td> <Td> Disputes : </Td> </Tr> <Tr> <Th> June 15 , 1846 </Th> <Td> The Oregon Treaty established the 49th parallel north west of the Lake of the Woods as the continental border ( so it did not include Vancouver Island ) with land held by the United Kingdom . The sharing of Oregon Country ended , and the United States portion became unorganized territory . <P> The treaty was vague on which strait should be the border between Vancouver Island and the continent , thus causing a dispute over ownership of the San Juan Islands . It specified `` through the middle of the said channel and of Fuca Straits , to the Pacific Ocean '' . </P> </Td> <Td> Northwestern North America : Disputes : </Td> </Tr> <Tr> <Th> September 22 , 1846 </Th> <Td> Following the capture on August 18 , 1846 , of Santa Fe , the capital of the Mexican territory of Santa Fe de Nuevo México , a code of laws known as the Kearny Code was created for the area . The region overlapped with Texas ' claim , though Texas had little to no control over the area outside of its eastern quarter . </Td> <Td> Unofficial change : </Td> </Tr> <Tr> <Th> December 28 , 1846 </Th> <Td> The southern portion of Iowa Territory , south of parallel 43 ° 30 ′ north and east of the Big Sioux River , was admitted as the twenty - ninth state , Iowa . The remainder became unorganized territory . </Td> <Td> </Td> </Tr> <Tr> <Th> March 13 , 1847 </Th> <Td> The District of Columbia retroceded Alexandria County back to Virginia . Congress passed the act on July 9 , 1846 , residents of Alexandria County were proclaimed by the president to have agreed to it on September 7 , 1846 , and Virginia took possession of the land on this date . </Td> <Td> </Td> </Tr> <Tr> <Th> May 29 , 1848 </Th> <Td> The southern bulk of Wisconsin Territory , mainly east of the St. Croix River , was admitted as the thirtieth state , Wisconsin . The remainder became unorganized territory . However , the citizens of the remainder decided to continue on with a civil government , and even elected a delegate to the United States House of Representatives who would be seated on January 15 , 1849 , essentially making this region a de facto continuation of Wisconsin Territory . </Td> <Td> </Td> </Tr> <Tr> <Th> July 4 , 1848 </Th> <Td> The Treaty of Guadalupe Hidalgo ended the Mexican -- American War and ceded a large parcel of land from Mexico , consisting of its territories of Alta California and Santa Fe de Nuevo México , and its claim to Texas . Due to a disagreement over the southern border of Santa Fe de Nuevo México , a border dispute began . </Td> <Td> Disputes : </Td> </Tr> <Tr> <Th> August 14 , 1848 </Th> <Td> Oregon Territory was organized from the unorganized territory that was formerly part of Oregon Country . </Td> <Td> </Td> </Tr> <Tr> <Th> February 13 , 1849 </Th> <Td> The boundary dispute between Iowa and Missouri known as the Honey War was resolved by the Supreme Court of the United States . The resulting border was the Sullivan Line that existed before the dispute , roughly splitting the two claims . </Td> <Td> </Td> </Tr> <Tr> <Th> March 3 , 1849 </Th> <Td> Minnesota Territory was organized from unorganized territory east of the Missouri River and the region that had been operating as de facto Wisconsin Territory . </Td> <Td> </Td> </Tr> <Tr> <Th> March 12 , 1849 </Th> <Td> A local government formed the State of Deseret and claimed a vast portion of the southwest , including most of the Mexican Cession . Though it petitioned to be admitted to the United States , the proposal was rejected and , in 1850 , Utah Territory was formed instead . The claimed area overlapped slightly with Texas ' claimed area , as well as part of Oregon Territory . </Td> <Td> Unofficial
<Table> <Tr> <Th> Date </Th> <Th> Event </Th> <Th> Change Map </Th> </Tr> <Tr> <Th> December 29 , 1845 </Th> <Td> The Republic of Texas was annexed and admitted as the twenty - eighth state , Texas . Texas brought with it a substantial territorial dispute with Mexico . While many sources state that Mexico recognized the independence of the eastern portion of Texas , the treaties were rejected by the Mexican government . Texas formally handed over sovereignty to the United States in a ceremony on February 19 , 1846 . The annexation led to the beginning of the Mexican -- American War a few months later . </Td> <Td> Disputes : </Td> </Tr> <Tr> <Th> June 15 , 1846 </Th> <Td> The Oregon Treaty established the 49th parallel north west of the Lake of the Woods as the continental border ( so it did not include Vancouver Island ) with land held by the United Kingdom . The sharing of Oregon Country ended , and the United States portion became unorganized territory . <P> The treaty was vague on which strait should be the border between Vancouver Island and the continent , thus causing a dispute over ownership of the San Juan Islands . It specified `` through the middle of the said channel and of Fuca Straits , to the Pacific Ocean '' . </P> </Td> <Td> Northwestern North America : Disputes : </Td> </Tr> <Tr> <Th> September 22 , 1846 </Th> <Td> Following the capture on August 18 , 1846 , of Santa Fe , the capital of the Mexican territory of Santa Fe de Nuevo México , a code of laws known as the Kearny Code was created for the area . The region overlapped with Texas ' claim , though Texas had little to no control over the area outside of its eastern quarter . </Td> <Td> Unofficial change : </Td> </Tr> <Tr> <Th> December 28 , 1846 </Th> <Td> The southern portion of Iowa Territory , south of parallel 43 ° 30 ′ north and east of the Big Sioux River , was admitted as the twenty - ninth state , Iowa . The remainder became unorganized territory . </Td> <Td> </Td> </Tr> <Tr> <Th> March 13 , 1847 </Th> <Td> The District of Columbia retroceded Alexandria County back to Virginia . Congress passed the act on July 9 , 1846 , residents of Alexandria County were proclaimed by the president to have agreed to it on September 7 , 1846 , and Virginia took possession of the land on this date . </Td> <Td> </Td> </Tr> <Tr> <Th> May 29 , 1848 </Th> <Td> The southern bulk of Wisconsin Territory , mainly east of the St. Croix River , was admitted as the thirtieth state , Wisconsin . The remainder became unorganized territory . However , the citizens of the remainder decided to continue on with a civil government , and even elected a delegate to the United States House of Representatives who would be seated on January 15 , 1849 , essentially making this region a de facto continuation of Wisconsin Territory . </Td> <Td> </Td> </Tr> <Tr> <Th> July 4 , 1848 </Th> <Td> The Treaty of Guadalupe Hidalgo ended the Mexican -- American War and ceded a large parcel of land from Mexico , consisting of its territories of Alta California and Santa Fe de Nuevo México , and its claim to Texas . Due to a disagreement over the southern border of Santa Fe de Nuevo México , a border dispute began . </Td> <Td> Disputes : </Td> </Tr> <Tr> <Th> August 14 , 1848 </Th> <Td> Oregon Territory was organized from the unorganized territory that was formerly part of Oregon Country . </Td> <Td> </Td> </Tr> <Tr> <Th> February 13 , 1849 </Th> <Td> The boundary dispute between Iowa and Missouri known as the Honey War was resolved by the Supreme Court of the United States . The resulting border was the Sullivan Line that existed before the dispute , roughly splitting the two claims . </Td> <Td> </Td> </Tr> <Tr> <Th> March 3 , 1849 </Th> <Td> Minnesota Territory was organized from unorganized territory east of the Missouri River and the region that had been operating as de facto Wisconsin Territory . </Td> <Td> </Td> </Tr> <Tr> <Th> March 12 , 1849 </Th> <Td> A local government formed the State of Deseret and claimed a vast portion of the southwest , including most of the Mexican Cession . Though it petitioned to be admitted to the United States , the proposal was rejected and , in 1850 , Utah Territory was formed instead . The claimed area overlapped slightly with Texas ' claimed area , as well as part of Oregon Territory . </Td> <Td> Unofficial
what gave the us the last land needed to expand to the pacific ocean
what gave the us the last land needed to expand to the pacific ocean
The Oregon Treaty
The Oregon Treaty