The Mountains to Sound Greenway is a scenic, historic and recreation corridor stretching along Interstate 90 from the Seattle waterfront, through the forests and rugged peaks of the Cascades, and into Central Washington. It's a scenic gateway to Washington's largest cities and a pathway to nature for growing city populations.

With the increasing population pressures in the greater Puget Sound region, this landscape could easily become a long strip of shopping malls, business parks and housing developments. The MTS Greenway Trust is the organization that works to protect this landscape from poorly planned growth to ensure continued access to recreation and a healthy environment.