The Ninth District contains the mostly rural eastern half of Thurston County, and is bordered by the Nisqually River to the northeast and Lewis County to the south. The cities of Yelm and portions of Lacey and Olympia are in the Ninth District, as well as the Nisqually Indian Reservation.

To the north is the Nisqually National Wildlife Refuge, an important stop over for migratory birds at the mouth the Nisqually River. Meanwhile, the Yelm prairie to the east has served as a crossroads for humans: first for Native American trails leading north from the Cowlitz River and the Bald Hills trail leading to Naches Pass over the Cascades. These trails were utilized by the Nisqually Indians, then fur traders, the British operators of the Hudson Bay Company, American settlers and eventually the Northern Pacific Railroad.