Neon gas station signs were pretty rare. Most places used porcelain steel with a light shining from above or below. Urban locations might get neon to cut through sign clutter (already a problem back then).

DX is long gone. An ordinary DX sign was still in its original location on Route 66 in Kansas until around 2010.

This sign is at Tulsa's Stokely Event Center: www.stokelyeventcenter.com.