Some of the posters go back as late as the 1890s. Many are valued at over a $1,000 – the most expensive is a travel promotion for Atlantic City valued between $10,000 and $15,000.

A 1939 Pan Am poster (left) features a Boeing Super Clipper 314 landing in a tropical lagoon; a 1932 poster advertises the industrial bombast of Italy’s new “super-express” ocean liners, the ...