20 Dollars WP 4-6-2 Pacific

Liberia's early 2000s commemorative program was nakedly commercial — coins like this were designed for the collector novelty market, not domestic circulation, and were typically sold through international distributors with no meaningful connection to Liberian monetary policy. The WP 4-6-2 Pacific locomotive type was the workhorse of American railroading from roughly the 1900s through the diesel transition, with thousands built by Baldwin, ALCO, and Lima for carriers across the continent.

The "WP" here almost certainly designates the Western Pacific Railroad's Pacific-type fleet.