United States 1931 Walter Hinton NC-4 Aviation Tour Signed Airmail Cover RPO

Cover franked with 5c Air Post, tied by SAN FRAN & LOS ANG RPO (Apr 16) duplex, with large handstruck cachet for the flight beginning at Toledo, Ohio and ending at the National Exchange Club convention in Memphis, Tennessee, signed "Walter Hinton" in black, scarce and attractive.