This summer put an enormous, moving audience on Atlanta's streets, and one local startup wants to sell ads to it. Purposers OOH, founded by Midtown-area entrepreneurs James and Keisa Manning, is rolling out purpose-built e-trikes, three-wheeled battery-powered cycles, mounted with digital advertising screens.

The pitch, per Hypepotamus, is targeting. Festival crowds, World Cup fans, and tourists are packing the BeltLine, Midtown, Buckhead, downtown, and the area around Mercedes-Benz Stadium. A static billboard cannot follow that foot traffic. An app-managed e-trike can roll to wherever the crowd is and swap what it shows on the fly.

Call them mobile billboards if you want, and plenty of people will find another set of glowing screens on the BeltLine a little much. But as a bet on where Atlanta's attention physically is this summer, the idea is hard to argue with.