When I saw this picture on line, the first thing I thought of was driving late at night in the late 50s and early 60s. That may not be an obvious leap, but it is valid. Here's why:
Back then, cars had radios that could only receive AM, and about the only stations that you could pick up at night were the 50 thousand watt clear channel stations like KOA in Denver or WOAI in San Antonio. Sometimes, driving across Texas, I could pick up WSB out of Nashville.
The one station you could pick up just about anywhere West of the Mississippi was XERF which broadcast from a 250 thousand watt transmitter across the river from Del Rio in Villa Acuña, Mexico. At times, the station featured country music (they were once the home of the Carter Family) and later Rock and Roll (Wolfman Jack) - but very late at night they broadcast evangelists like Charles Jessup from Ft. Worth.
I can still remember him urging listeners to "Put your hands on the Radio" to be healed, and promising that for a small donation, he would send you an "autographed picture of Jesus Christ."