1940 image from https://sites.google.com/site/lamoviepalaces/sgvalley .
Two sources say that the Alhambra Theatre and Annex (shown above) dates from 1939:
“Edwards did just about everything at the theater from selling tickets and popcorn to running the projector. In 1939, he built what is believed to be the first multiscreen theater in the country the Edwards Alhambra Twin Cinema. There is a plaque commemorating it at the Atlantic and Main location, where the company now operates a 10-screen theater.” https://www.newspapers.com/newspage/92373858/ .
First in the world was in England in 1930. “The first in the United States was the Alhambra Twin in Alhambra, Calif. in 1939 .” Robertson’s Book of Firsts: Who Did What for the First Time by Patrick Robertson.
However, other authoritative sources say it was 1940. The photo above shows the movie Maryland on the marquee that premiered in 1940 but that doesn’t mean that the twin theatre hadn’t opened in the year before.
Read all about it at the links.