San Anto (“San Antonio” in Chicano slang)

“San Anto” means “San Antonio” in Chicano slang. This slang (called “Caló”) was popular with Mexican-Americans in the 1970s, when several citations of “San Anto” first appear.
 
 
Wikipedia: List of Chicano Caló words and expressions
The following is a list of Chicano slang words and expressions, known as Caló, also spelled “Calo” and “Kalo” by modern Chicano youth. It does not list words and expressions of the language of the Spanish Roma people, which is also called Caló, except where these have been incorporated into Chicano Caló. Nor does it list Mexican slang words and expressions unless they have originated in Pachuco Caló or have been incorporated into it with altered meaning. A few words can be traced to the Nahuatl language of the Mexicas (Aztecs).
(...)
San Anto
San Antonio, Texas
 
Guide to Prison Slang
TEXAS
DEPARTMENT OF CRIMINAL JUSTICE
INSTITUTIONAL DIVISION
THE CORRECTIONAL OFFICERS
GUIDE TO
PRISON SLANG
By Lt. Avery & P. Anderson CoIII
(...)
SAN-ANTO: Hispanic slang, for San Antonio, Texas.
 
Google Books
Barrio Language Dictionary:
First Dictionary of Caló
by Dagoberto Fuentes and José Armando López
Los Angeles, CA: Southland Press
1974
Pg. 134:
SAN ANTO San Antonio, Texas.
 
Google Books
Regional Dictionary of Chicano Slang
by Librado Keno Vasquez and Maria Enriqueta Vasquez
Austin, TX: Jenkins Publishing Company
1975
Pg. 70:
SAN ANTO - San Antonio, Texas
 
Smithsonian Archives of American Art
Oral History Interview With
Jacinto Quirarte
In Helotes, Texas
August 15 & 16, 1996
Interviewer: Paul J. Karlstrom
(...)
PK: Archives of American Art, Smithsonian Institution, an interview with Jacinto Quirarte, an art historian, professor at the University of Texas, San Antonio, where this interview is being conducted on August 15, 1996. This is Session 1, Tape 1, Side A. The interviewer is Paul Karlstrom and this is part of a Latino Documentation Project.
(...)
JQ: In Chicano slang, San Antonio would be called “San Anto” and Los Angeles would be called “Los,” and San Francisco would be [“San Fra” (Sahn Frah)]—I mean that kind of thing, as this wave of Aztecisms in the early seventies led to the use of Aztlán for all of the states in the Southwest.
 
Google Books
The Women’s Kama Sutra
by Nitya Lacroix
Albany, NY: SUNY Press
2002
Pg. 259:
Chicanos have “renamed” most places in the Southwest and the West heavily populated by Mexican Americans (the original site of Aztlán) with terms that are used for in-group communication, and sometimes even for addresses: “Sanjo” (San Jose), “Califas” or “Califaztlán” (California), “San Anto” (San Antonio), “E.P.T.” (El Paso, Texas),  “Ariztlán”( Arizona).