Coke, Pepsi, and Dr. Pepper are rolling out the vending machines next year. They will be in government buildings in Chicago and San Antonio, Texas.
On Monday, Mayor Rahm Emanuel offered a "wellness competition" between the cities.
"This entire campaign and challenge between Chicago and San Antonio is built on the idea of personal responsibility. You'll improve your own health as well as the health of the taxpayers," said Emanuel.
The city's employees who rate higher on key wellness factors will be eligible for cash rewards that are part of a grant from the American Beverage Association, which represents the soft drink makers.