Fort Scott American Legion Claire C Harkey Post 25 was organized on June 30, 1919 and received its permanent charter date on September 2, 1920. The roster of charter members lists 71 members.

PFC Claire C Harkey was a World War 1 Bourbon County soldier, who was killed in action on September 26, 1918 while assigned to Company G, 137th Infantry, 35th Division, AEF. PFC Harkey was buried in Meuse-Argonne American Cemetery. 

In 1988, members of Fort Scott American Legion Joseph B Thompson Post 30 merged their Post with Post 25. Post 30 was a black Post whose membership had dwindled to just a few members in 1988. 

Corporal Joseph B Thompson was a Bourbon County soldier who died of pneumonia in France on May 23, 1918. Corporal Thompson was buried in the Fort Scott National Cemetery. 

The newly merged Post was called American Legion Fort Scott Thompson-Harkey Post 25. 

The Fort Scott American Legion has met in Memorial Hall for most of its existence and the City of Fort Scott has given the American Legion two rooms to use for meetings and events. Both rooms are currently undergoing renovation at this time. 

Fort Scott Thompson-Harkey Post 25 has grown by 33 members since May 2017 and has recently established a Sons of the American Legion Squadron.  In 2018, Post 25 received one of only two Post Excellence awards for the Department of Kansas. 

Legionnaire James Streeter, Korean War Army Vet, has 73 years of continuous Legion membership as of the 2019 Legion year, making him the Legionnaire with the most continuous membership years in Post 25.