The first flavoured crisps in the United States, barbecue flavour, were being manufactured and sold by 1954. Herr’s and Ley’s both produced crisps with that flavour in the 1950s. It was the only flavour available in the United States other than the conventional salted chip until the introduction of Sour Cream & Onion in the late 1970s.
US first: Barbecue flavour crisps
Museum of Crisps 