“San Antonian” is the name of an inhabitant of San Antonio, Texas. The name “San Antonian” has been cited in print since at least 1847.
 
 
Wikipedia: Demonym
San Antonio → San Antonian
 
Wikipedia: San Antonio
San Antonio ( /ˌsænænˈtoʊni.oʊ/) is the seventh-largest city in the United States of America and the second-largest city within the state of Texas, with a population of 1.33 million. Located in the American Southwest and the south–central part of Texas, the city serves as the seat of Bexar County. In 2011, it was estimated to be the 24th largest metropolitan area in the U.S. with a population of 2.2 million according to U.S. Census Bureau figures tabulated by Business First. San Antonio has characteristics of other western urban centers in which there are sparsely populated areas and a low density rate outside of the city. It was the fourth-fastest growing large city in the nation from 2000 to 2006 and the fifth-fastest-growing from 2007 to 2008. The San Antonio–New Braunfels metropolitan area has a population of over 2.14 million based on the 2010 U.S. Census, making it the 25th-largest metropolitan area in the United States and third-largest in Texas.
 
The city was named for San Antonio de Padua, whose feast day is on June 13, when a Spanish expedition stopped in the area in 1691. Famous for Spanish missions, the Alamo, the River Walk, the Tower of the Americas, the Alamo Bowl, Marriage Island and host to SeaWorld and Six Flags Fiesta Texas theme parks, the city is visited by approximately 26 million tourists per year according to the San Antonio Convention and Visitors Bureau. The city is home to the four-time NBA champion San Antonio Spurs and the annual San Antonio Stock Show & Rodeo, one of the largest in the country.
 
San Antonio has a strong military presence—it is home to Fort Sam Houston, Lackland Air Force Base, Randolph Air Force Base, and Brooks City-Base, with Camp Bullis and Camp Stanley outside the city. Kelly Air Force Base operated out of San Antonio until 2001, when the airfield was transferred over to Lackland AFB and the remaining portions of the base became Port San Antonio, an industrial/business park. San Antonio is home to five Fortune 500 companies and the South Texas Medical Center, the only medical research and care provider in the South Texas region.
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Demonym San Antonian
 
Free Merriam-Webster Dictionary
San An·to·nio geographical name \ˌsan-ən-ˈtō-nē-ˌō\
Definition of SAN ANTONIO
1river ab 200 miles (322 kilometers) S Texas flowing SE into Gulf of Mexico
2city S Texas on San Antonio River pop 1,144,646
— San An·to·ni·an \-nē-ən\ noun
       
The Portal to Texas History
11 December 1847, Texas Presbyterian (Houston, TX), pg. 2, col. 3:
We San Antonians are getting along pretty much as we were when you visited us in May last, ...
 
5 September 1849, Augusta (GA) Chronicle & Sentinel, “Letter from Texas,” pg. 2, col. 1:
The San Antonian Texan of the 10th inst. learns from a gentleman rom the Presidio del Norte, that Capt. Veatch and his party, together with some other Americans, were in the State of Chihuahua.
 
24 July 1868, Flake’s Bulletin (Galveston, TX), pg. 4, col. 2:
We have received “No. 2” of a new tri-weekly issue, called the San Antonian. Its name indicates its birth place. Its politics is Democratic. It appears to be moderate in tone and gives promist of ability.
 
OCLC WorldCat record
Representative San Antonians : city builders ; brief resume of the city of San Antonio and a limited number of prominent men who have done their full part to make the Texas metropolis
Author: Harry J Boswell
Publisher: San Antonio, Tex. : San Antonio printing co., 1913.
Edition/Format:  Book : English
 
OCLC WorldCat record
San Antonio, land of romance.
Author: San Antonians (Musical group)
Publisher: San Antonio : San Antonians Inc., [ca. 1930]
Edition/Format:  Book : English
 
OCLC WorldCat record
The San Antonian.
Author: Greater San Antonio Chamber of Commerce.
Publisher: [San Antonio, Tex., Greater San Antonio Chamber of Commerce]
Edition/Format:  Journal, magazine : Periodical : English