The Alamo Electronic Corporation was originally set up by Southland Music and Charles Eilenberg post World War II (ca. 1947), making record players and battery-powered radios. They went on to produce musical instrument cases and around 1949 or 1950 moved on to making amplifiers and lap steel guitars. The first Alamo solid body guitars appeared around 1960 and Alamo guitars were made until around 1970.  Alamo amplifiers were made until the early 1980s, when Alamo combined with a company called Southwest Technical Products.

A modern day Alamo Guitars brand existed (as part of Robin) from 1999-2010 but was not associated with the original brand.

Source: Alamo catalogs 1950s -1960s

Source: Vintageguitar.com