Thomson won 32 midget features in 1948 as well as the UCOA New England title. He repeated as UCOA champion in 1950.

He won the AAA Eastern Midget Championship in 1952 and started in his first Indy 500 the next year. Overall Thomson cometed in eight Indy 500's. He placed 4th in '55, 3rd in '59 and 5th in 1960. He was the pole sitter in the 1959 Indy 500.

In 1957 he won the first 100 mile race on dirt at Langhorne Speedway in less than one hour in a champ car. His speed was 100.74 MPH.

He lost his life at Allentown PA in a 1960 Sprint Car event.