Green’s Dictionary of Slang

a street-seller of cheap articles.

1922–24		O.O. McIntyre White Light Nights 2: If you ask the brown-derbied ‘pitch men’ who sell trifling gimcracks along the curb, they will tell you New York is the biggest sucker town in America.
1926		P. White ‘Circus List’ AS I:5 283/1: Pitchman, a man who sells novelties on the circus lot or on the streets adjacent to the lot.
1931		Irwin Amer. Tramp and Und. Sl. 147: Pitchman. – A fakir or peddler of novelties or small pieces of merchandise who works on the street, in empty lots, or on a circus or carnival lot. He is said to be working a ‘low pitch’ when standing on the ground; and a ‘high pitch’ when standing on a platform or in an automobile or wagon.
1948		Chicago Trib. 25 Jan. 17/1: For several seasons she went buzzing ahead of the New York company with her enthusiastic pitchwoman spiels [DA].
1953		F. Brown Madball (2019) 6: All right to work for and a damn good pitchman, but pretty dull company.
1962		Ragen & Finston World’s Toughest Prison 813: pitchman – A fakir or peddler of novelties or small pieces of merchandise who works in the streets, etc.