In June of 1871 Chief Seltice of the Coeur d'Alene tribe and German settler Frederick Post, made a verbal agreement. Post was granted 200 acres of native land to build a sawmill. As a part of the agreement Post would provide lumber to the tribe. The purchase of the land is preserved in a pictograph on a granite cliff in Treaty Rock Park. It is unclear whether they signed the rock as the initial contract or for later as a memorial. According to one source, Post Falls' treaty rock may be the only place in the United States where a contact with a native tribe was signed on rock.
Post Falls began to grow rapidly from the expansion of the lumber mills. Frederick Post built the areas first gristmill at Spokane Falls, but soon returned to Post Falls. Logs were transported to the mill by horse, water and later on the railroad and eventually the highway. After the mill burned down [when], the population shrank drastically. The Post Falls Dam site is positioned at the site of the old mill today. Post Falls used to provide irrigation to Spokane Valley and also electricity to the mining developments in the Silver Valley.
Treaty Rock was placed on the National Historic Register is 1992, representing the coming together of two cultures. This four acre plot offers paved trails and picnic areas. The site is located behind apartment complexes north of I-90 tucked away in the tall trees. Over the years the site has been struck by vandalism, so Plexiglas was placed on the face of the engraved rock to protect it. Cameras were installed to curb the vandalism and police officers continue to monitor the area.