Rubuta ci gaba ga wannan sakin layi - Horowitz ya kasance babban dan wasa a Amurka a cikin shekarun 1930 da 1940. Ya kasance US Open Champion a 1936, 1938, da kuma 1943. A cikin 1941, ya rasa wasa (+ 0-3 = 13) tare da Samuel Reshevsky don Gasar Chess ta Amurka. Ya taka leda a tawagar Amurka a gasar Chess Olympiads hudu, a 1931, 1935
, 1937, da 1950; na farko uku daga cikinsu sun lashe ta Amurka A cikin sanannen Amurka da USSR wasan kwaikwayo na rediyo na 1945, Horowitz ya zira kwallaye daya daga cikin nasara biyu kawai ga Amurka ta hanyar kayar da GM Salo Flohr. Ya raba "karamin wasan" na wasanni biyu da Flohr, kuma a cikin bugun 1946 na wannan taron, ya raba karamin wasan nasa da Isaac Boleslavsky.