
Kansas City Southern No. 503 is a Class 500 4-6-0 "Ten Wheeler" type steam locomotive built for the Louisiana & Arkansas Railroad by Baldwin in 1920.
The Louisiana Midland picked up #503 in 1948, and the Texas & Northern #502 in 1949.
It was transferred to the LM's sister company, the South Shore Railway at Jackson, LA, in 1950. When, in 1957, Port Arthur expressed an interest in obtaining a steam engine for display, the Kansas City Southern bought #503 from the South Shore and sold it to the City of Port Arthur for $1. The Lions Club of Port Arthur sponsored restoration. It is on display in Bryan Park and, although lettered KCS #503, it never operated as a KCS engine.
In 2018, the locomotive was in danger of being scrapped due to contaminated soil on the display site. A GoFundMe was set up to acquire the locomotive from the city of Port Arthur for potential restoration. The acquisition, however, fell through and the GoFundMe was shifted towards acquiring three pieces of equipment from the Indiana Transportation Museum and funding NKP 587's relocation and other steam preservation. The 503 was eventually moved 120 feet to a new pad so the soil underneath the old site could be decontaminated.