Mezue ahịrịokwu na-esonụ: Horowitz bụ onye na-eduga na United States n'afọ ndị 1930 na 1940. Ọ bụ onye mmeri US Open na 1936, 1938, na 1943. N'afọ 1941, o meriri Samuel Reshevsky n'asọmpi U.S. Chess Championship (+0−3=13). O so n'otu ndị otu mba Amerịka n'egwuregwu Olimpik Chess ugboro anọ, n'afọ 1931, 1935, 1937, na
1950; nke mbụ n'ime ha atọ meriri site na US Na a ma ama USA vs. USSR redio egwuregwu egwuregwu chess 1945, Horowitz gbatara otu n'ime naanị mmeri abụọ maka US site na imeri GM Salo Flohr. O kewara "obere egwuregwu" ya nke egwuregwu abụọ megide Flohr, na mbipụta 1946 nke otu ihe ahụ, kewara obere egwuregwu ya megide Isaac Boleslavsky.