Radio waves don’t obey bor­ders, and sta­tions have been tak­ing advan­tage of this fact since the dawn of the medi­um – often despite the rules of gov­ern­ment reg­u­la­tors where the sig­nals go. Dr. Kevin Cur­ran of Ari­zona State Uni­ver­si­ty has been study­ing bor­der radio sta­tions exten­sive­ly, mak­ing it the sub­ject of his doc­tor­al dis­ser­ta­tion. Every­one has a ton of radio nerd fun as he takes us back to the 1920s, when Cana­di­an and U.S. reg­u­la­tors struck a treaty to split up the AM dial and lim­it max­i­mum broad­cast pow­er, but left out Mex­i­co. That opened up an oppor­tu­ni­ty for sta­tions in that coun­try to cov­er the con­ti­nent with hun­dreds of kilo­watts, attract­ing broad­cast­ers from north of the bor­der want­i­ng to take advan­tage. Many infa­mous and col­or­ful per­son­al­i­ties were amongst this group, from Dr. John Brink­ley, who pro­mot­ed goat glands to cure male poten­cy prob­lems, all the way to man named Bob Smith – lat­er known as Wolf­man Jack – who blast­ed rock and roll that most Amer­i­can sta­tions wouldn’t touch. Dr. Cur­ran explains why sta­tions along the Mex­i­can bor­der remained pop­u­lar with U.S. broad­cast­ers even after that coun­try low­ered max­i­mum pow­er lev­els, in treaty with its north­ern neigh­bor. He also explores the rela­tion­ship of U.S. sta­tions to Cana­di­an mar­kets, where sta­tions are more high­ly reg­u­lat­ed. If you’ve ever won­dered why radio is dif­fer­ent along the bor­der, you’re curios­i­ty will be satisfied.