The logo you see at the top of this webpage is the third logo for the American Public Works Association since its formation in 1937. In each case, the logo primarily depends on the weight of the acronym APWA to assert its identity.
First there was the two separate organizations, American Society of Municipal Engineers and International Association of Public Works Officials, each with its own logo. In 1937, those organizations merged to form the American Public Works Association.
The first APWA logo shadowed the shape and fonts of the logos for the predecessor organizations. It used gold lettering on a blue background.