1926 Haven High School Football Team defeated Sylvia 256-0 and is listed in Ripley's Believe it or Not as the world record for highest scoring football game on record.
Astoria High School, Astoria Oregon football defeated Molalla High School, Molalla, Oregon 100 to 6 in September 1970.
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Basketball:
According to Wiki.answers, the highest scoring high school basketball game was 302 to 4. It didn't list the teams involved.
Two high school basketball teams in 2008 in Florida: Naples 91, Estero 0.
Lancers of RAF Lakenheath vs SHAPE High School basketball ended with a score 8-2.
And don’t forget the biggest blowout in college football history, on October 7, 1917:
Georgia Tech 222
Cumberland 0