#203 is a legacy from an era of rapid growth for the railroad. During a portion of this period, the Soo Line greatly expanded its caboose fleet and shared a single caboose design with its leased subsidiary, the Wisconsin Central. Between 1906 and 1913, 115 of these cabooses were built by the American Car & Foundry Co. Also in 1913, the Soo Line constructed nine additional cabooses at its Shoreham Shops, bringing the total complement of cabooses built to the design to 124.

#203 was delivered with the initial order of 35 cars built by AC&F in September 1906, and included car numbers 127, 143, 149, 150, and 198 through 228. The 100-series numbered cars were built as replacements for earlier retired cabooses.

All of these cabooses were originally built with a wood underframe and truss rods. The most unusual feature was the single window concept employed on one side of the main body. The interior arrangement of the caboose did not lend itself to additional windows on this side.

Between 1924 and 1928 new steel center sills were applied to these cabooses at the Shoreham Shops. However, the truss rods and the wood beam arch bar trucks were retained. Also, at Shoreham about this time, the Soo Line applied a new cupola design to these cars on an as needed basis. The new cupola was built with a random variation consisting of either one or two windows on the side. The #203 has a single window on each side of the cupola. 

The #203’s last assignment was to be teamed up with the Soo Line’s rotary snowplow that was based out of Gladstone, MI. In March 1966 the Soo Line sold the #203 (for $325) to a member of Mid-Continent and the car was moved to North Freedom. Its interior was modified to make it more suitable for a bunk facility. In December 2018 the Ginter Family generously donated the Soo Line #203 to the museum. The caboose is presently being accurately restored back to the Soo Line era. Once completed the car will go on public display and occasionally see service at Mid-Continent.