Operating Era: 1912-1952. Chicago, Rock Island & Pacific, Rock Island, Arkansas & Louisiana, Linde Air Products. Rock Island ordered 950 50' cars from Western Steel Car & Foundry and Pullman in 1912. The were, to our knowledge, the first 50' SS cars built. However, the fishbelly underframe of the previous decade was retained as a safety measure, resulting in an unusual looking car. Side framing was a combination of Z-bars and channels, another unusual technique. Side doors were double for a 10' opening. The A end has a full steel door while the B end was SS. In 1925/6 the end doors were removed from most cars; however, a few retained them throughout their lives. In 1928 the side doors were rebuilt as 1 and 1/2, 6' and 4' respectively. In 1930 many cars were given 3 types of new end doors and some cars received 12' wide side openings. We currently have no data on these 1930 revisions. In 1936 some cars were transferrred to auto body loading. A photo of one car shows strengthened side panels and a new roof. As far as we can tell, all versions of the revised cars ran ran concurrently, some into the late1940's. Cars were slowly sold off in the 1940's, some showing up as single door cars on the Bamberger RR. Some were converted to pulpwood service and some were used in MOW.