One of the best roadside attraction/gas station postcards I have seen is this one of the Fairyland Service Station at Rock City on Lookout Mountain TN. The back of the postcard offers a free 26x22 picture of Lovers Leap (suitable for framing!) with a gas fill.
Rock City tourist was established in 1932 by Garnet and Frieda Carter. It consisted of trails around rock formations (with fairyland statues and wildflower plantings) ending at "Lover's Leap". The attraction was promoted by signs painted on barns as far north as Michigan.
Rock City Barn Tour - Rock City
This postcard can be found in my eBay store here: FAIRYLAND GAS SERVICE STATION ROCK CITY LOOKOUT MOUNTAIN TN
And in my bidStart Store here: FAIRYLAND GAS SERVICE STATION ROCK CITY LOOKOUT MOUNTAIN TN
I have other roadside postcards (motels, gas stations, tourist attractions, restaurants listed in my eBay Store: Motels, Restaurants, Roadside