Tacoma Rail directly connects with three railroads for freight service. These key partners are:
- BNSF Railway (BNSF), which serves the western half of the United States and connects with Tacoma Rail at Tacoma, East Olympia and Centralia, WA
- Union Pacific Railroad (UP), which also serves the western United States and connects with Tacoma Rail at Tacoma and Centralia, WA
- The Puget Sound and Pacific Railroad (PSAP), a shortline serving western Washington between Centralia, Hoquiam, Bremerton and Bangor, and connects to Tacoma Rail at Centralia, WA.
- Port of Tacoma, a major gateway to Asia and Alaska. The Port of Tacoma is a leading North American seaport, handling more than $36 billion in annual trade and nearly 2 million TEUs (Twenty-foot Equivalent container Units) in 2007. The Port is the seventh largest container port in North America.
- Port of Olympia, which serves the Thurston County community in a wide variety of ways, and is a leading part of the area's economic development efforts.
More partners include:
- Washington State Department of Transportation
- Washington State Department of Ecology
- Federal Railroad Administration
- Federal Emergency Management Agency
- Puget Sound Clean Air Agency
- Olympic Region Clean Air Agency



