Question: When did the state assigned area code 575 become a part of the United States?

full_context: Document 1: Area code 252: Area code 252 designates a telephone number plan area (NPA) in the North American Numbering Plan that consists of the northeastern corner of the State of North Carolina, and includes the municipalities of Kinston, Elizabeth City, Greenville, Henderson, Kitty Hawk, New Bern, Roanoke Rapids, Rocky Mount, Morehead City and Wilson. It was split from area code 919 on March 22, 1998.
Document 2: New Mexico Territory: The Territory of New Mexico was an organized incorporated territory of the United States that existed (with varying boundaries) from September 9, 1850, until January 6, 1912, when the remaining extent of the territory was admitted to the Union as the State of New Mexico, making it the longest - lived organized incorporated territory of the United States, lasting approximately 62 years.
Document 3: Area code 607: North American area code 607 is a state of New York telephone area code servicing parts of its Southern Tier (which borders Pennsylvania). It was split from parts of area codes 315 and 716 in 1954. Initially, in the late 1940s, area codes with a middle digit of ``0 ''(x0x - xxx - xxxx) were assigned only to jurisdictions covering an entire state. Along with 507 in Minnesota and 606 in Kentucky, 607 was among the first such area codes to be added to a jurisdiction.
Document 4: New Mexico: Inhabited by Native Americans for thousands of years before European exploration, it was colonized by the Spanish in 1598 as part of the Imperial Spanish viceroyalty of New Spain. It was named Nuevo México after the Aztec Valley of Mexico by Spanish settlers, 223 years before the establishment of the present - day country of Mexico. The present - day state of New Mexico was not named after, nor is it a part of, Mexico. Its geographic characteristics made settlement and effective political control difficult which prompted Mexico's invasion and control of the area from 1824 to 1846. New Mexico's Spanish origins made cultural integration with Mexico unsuitable, which sparked the Revolt of 1837 and a growing economic association with the expanding United States. The 1848 Mexican -- American War indirectly capitalized on this tension and created the U.S. New Mexico Territory. It was admitted to the Union as the 47th state on January 6, 1912.
Document 5: Area codes 715 and 534: North American telephone area codes 715 and 534 are state of Wisconsin area codes covering most of the northern part of the state.
Document 6: Florida Territory: The Territory of Florida was an organized incorporated territory of the United States that existed from March 30, 1822, until March 3, 1845, when it was admitted to the Union as the State of Florida. Originally the Spanish territory of La Florida, and later the provinces of East and West Florida, it was ceded to the United States as part of the 1819 Adams -- Onís Treaty. It was governed by the Florida Territorial Council.
Document 7: Area codes 587 and 825: Area codes 587 and 825 are telephone area codes that cover all of Alberta, Canada, in addition to the incumbent codes, southern Alberta's 403 and northern Alberta's 780. Numbers in area code 587 started being allocated in late 2008. The new area codes overlay 403 and 780 simultaneously, covering the entire province, and make 10 - digit dialing necessary throughout Alberta.
Document 8: Area codes 508 and 774: Area codes 508 and 774 are North American Numbering Plan (NANP) telephone area codes for the U.S. state of Massachusetts. This service area currently includes south - central and most of southeastern Massachusetts (LATA code 128). It includes Worcester, Outer south & southwest Greater Boston (such as the MetroWest region), as well as Fall River, New Bedford, Cape Cod, Martha's Vineyard, and Nantucket.
Document 9: Dakota Territory: The Territory of Dakota was an organized incorporated territory of the United States that existed from March 2, 1861, until November 2, 1889, when the final extent of the reduced territory was split and admitted to the Union as the states of North and South Dakota.
Document 10: Area code 575: Area code 575 is an area code in the U.S. state of New Mexico. It serves the remainder of the state outside the Albuquerque, Santa Fe, Farmington, and Gallup metropolitan and micropolitan areas, which remain in area code 505. The new code became effective on October 7, 2007, splitting from area code 505.
Document 11: Area code 956: North American area code 956 is a state of Texas telephone area code for numbers in the Brownsville, McAllen, Laredo and South Padre Island areas. It was created May 25, 1997, in a split from area code 210.
Document 12: Area codes 978 and 351: Area code 978 was created as a split from area code 508 on September 1, 1997 and covers north central and most of northeastern Massachusetts (LATA code 128). Use of 978 became mandatory February 1, 1998. Prior to when this area was served by 508 (July 1988), it was served only by the 617 area code, along with the rest of the eastern two - thirds of the state. 351 has been sharing the service area since May 2, 2001. Since then, 10 digit local dialing is mandatory.
Document 13: New Mexico: Inhabited by Native Americans for thousands of years before European exploration, it was colonized by the Spanish in 1598 as part of the Imperial Spanish viceroyalty of New Spain. In 1563, it was named Nuevo México after the Aztec Valley of Mexico by Spanish settlers, 223 years before the establishment and naming of the present - day country of Mexico; thus, the present - day state of New Mexico was not named after the country today known as Mexico. Its geographic characteristics made settlement and effective political control difficult which prompted Mexico's invasion and control of the area from 1824 to 1846. New Mexico's Spanish origins made cultural integration with Mexico unsuitable, which sparked the Revolt of 1837 and a growing economic association with the expanding United States. The 1848 Mexican -- American War indirectly capitalized on this tension and created the U.S. New Mexico Territory. It was admitted to the Union as the 47th state on January 6, 1912.
Document 14: Southwest Territory: The Territory South of the River Ohio, more commonly known as the Southwest Territory, was an organized incorporated territory of the United States that existed from May 26, 1790, until June 1, 1796, when it was admitted to the United States as the State of Tennessee. The Southwest Territory was created by the Southwest Ordinance from lands of the Washington District that had been ceded to the U.S. federal government by North Carolina. The territory's lone governor was William Blount.
Document 15: Utah Territory: The Territory of Utah was an organized incorporated territory of the United States that existed from September 9, 1850, until January 4, 1896, when the final extent of the territory was admitted to the Union as the State of Utah, the 45th state.
ground_truth: January 6, 1912
sub_queries: where is the area code 575 located in Answer: New Mexico
when did New Mexico become part of the us Answer: January 6, 1912