As the need for more durable and longer lasting cabs grew, Checker went shopping for a stronger chassis to fit their requirements. In 1920 Checker awarded the Commonwealth Motor Co. a contract to assemble taxicabs using bodies supplied by another Joliet based company called Markin Auto Body Corp. owned by Morris Markin. Morris Markin became involved with the company after lending $15,000 to a friend who ran a small taxicab body plant. Later, to protect his investment, Mr. Markin took over the Company, which became the Markin Auto Body Corp. He merged with the faltering Commonwea1th Motor Co. at the end of 1921, and by May of 1922 the Checker Cab Manufacturing Co. was born.

In 1922 when the Checker Cab Manufacturing Co. was founded and located in Joliet, IL, production was set for three taxicabs a day and held there for several months building the Model "C" By January of 1923 production was up to 112 cabs a month, working the staff seven days a week. By the end of March more than 600 Checker cabs were on the streets of New York. Checkers were beginning to be recognized. To help in sales and to provide service, the Mogul-Checker Cab Sales Co. was created in New York City.

With growing pains and lack of room, Checker moved to Kalamazoo at its present location in April of 1923 taking over the old Handley-Knight Co. and Dort Body Plant. On June 18, 1923 the first Checker rolled off the assembly line in Kalamazoo. It was a banner day for Checker, which now employed 700 people.

In 1924 Checker production was increased to 4,000 units for the year. New Series "E" was introduced with a 40 HP rating. There were two models. The Landau sold for $2,440 and the limousine for $2,340. As the spring of 1925 came, production was at an unprecedented high of 75 units per week.