Though it has since become the largest organization of its kind, Kaiser was not the first HMO. In its modern form, the HMO combines a large group practice, contracts with employers to care for a group of workers, and a prepayment plan for both hospitals and group practices. The first "contract doctor" system in the West was orchestrated by Dr. Raymond G. Taylor, who created a temporary healthcare system from 1908 to 1912 on behalf of the Los Angeles Board of Public Works to care for the 10,000 workers on the Los Angeles Aqueduct project. The first group prepayment plans appeared in 1929 in response to the onset of the Great Depression. That year, Baylor University started a hospital prepayment plan, the first of several which would ultimately join together to become the Blue Cross insurance network. In Oklahoma, Dr. Michael Shadid recruited local farmers around Elk City, Oklahoma into a small consumer healthcare cooperative.