First recorded by Alvino Rey & His Orchestra (US #1 Feb 1942).
Also performed by Gene Autry (1942).
Other hit versions by Ted Weems & His Orchestra with Perry Como (US #23 Feb 1942), Bing Crosby with Woody Herman & His Woodchoppers (US #3 March 1942), Horace Heidt & His Musical Knights (US #7 March 1942), The Merry Macs (US #11 March 1942), Duane Eddy (US #78/UK #19 1962).
Also recorded by Gene Autry (1944), Bob Wills (1955), Ray Charles (1960).
From the wiki: “‘Deep in the Heart of Texas’ was written by June Hershey with music by Don Swander, with a title taken from a movie Western of the same name starring Tex Ritter. (The song was not performed in that particular movie, but would make an appearance in the Western movie Heart of the Rio Grande, released in 1942, sung by movie cowboy Gene Autry.)
“The first recording was by Alvino Rey and his orchestra, on November 21, 1941. It first charted in early 1942, eventually spending five weeks at #1 on the Hit Parade. The song was covered by Ted Weems & His Orchestra (with Perry Como on vocals) on December 9, 1941 for Decca Records, also released in early 1942 as the flip-side to ‘Ollie Ollie Out’s in Free’.