The city is requiring that food-truck operators keep a copy of the map in their vehicles "to show to any police officers or license-collector representatives that you are in an allowed spot."

While a number of approved areas remain within the vending district, some food-truck owners say their options have become limited.

"Like any new industry or trend, as soon as everyone jumps in, the regulations follow, which often makes sense. In this case, I think the city is over-regulating," Pi Pizzeria owner Chris Sommers said. "They do need to protect existing businesses, but the 200-foot rule plus the silly Cardinals and Convention Zones are too much."

Pi has operated a food truck in the city since 2010 and plans to open a brick-and-mortar restaurant next month in the new Mercantile Exchange building at Sixth Street and Washington Avenue.

"Trucks have been incredibly successful at getting people out of their offices, onto the streets, spending money and giving the appearance of life in downtown St. Louis," Sommers said. "Unfortunately, these regulations will keep trucks out of downtown and more pedestrians in their offices."

A spokeswoman for Mayor Francis Slay said the city would continue to try to work with food trucks and other downtown vendors.