Along with Crerar as a member of Jesup's new railroad house was a John S. Kennedy. The firm followed the infant industry and greatly prospered. As the Michigan Southern Railroad and the Michigan Central Railroad came to Chicago in 1852, it soon became apparent that not New York but Chicago would become the capital of the railroad industry. From Jesup's firm, J. McGregor Adams was sent to Chicago, where the branch plant expanded. Adams was soon joined by Crerar as co-junior partners managing the lucrative Chicago branch. In 1863 Adams and Crerar succeeded to the title and established their own firm of Crerar, Adams and Co., retaining however, the old title until 1868. In that year they first advertised themselves as "Crerar, Adams & Co., manufacturers and dealers in railroad supplies and contractors' materials, 11 and 13 Wells Street." This location was destroyed by the 1871 fire, situating itself temporarily in a "mere shanty" and then at the Robbins Building, where it would continue until Crerar's death.