Chicago — Potbelly Corporation, a neighborhood sandwich shop concept, has signed three new franchise agreements. Over the last 6 months, the company signed franchise agreements that, when fully built out over the coming years, will nearly double its franchise footprint with multi-unit development deals for a total of 38 units spanning Las Vegas; Tampa, Florida; and the Carolinas. In addition, Potbelly has opened a number of franchise stores this year that are driving brand penetration across several areas of the country, including recently opened shops in Irvine, Calif.; Odessa, Texas; …