Starting next Wednesday in Portland, public transit riders can say goodbye to paper tickets and hello to proof of payment via your smartphone.

TriMet, Oregon’s largest provider of bus, light rail and commuter rail transit services, will debut its new e-ticket app next week. Essentially, the free app eliminates the need to purchase paper tickets from a machine and allows you to easily buy transit fares using your Android device or iPhone.

Portland is the first city in the U.S. to implement this system-wide. Places like Boston and New Jersey have implemented similar mobile ticketing tools, but for just one mode of transportation at a time.

The app was built by GlobeSherpa, a Portland-based provider of secure mobile ticketing software and services that landed a $1.3 million round led by The Oregon Angel Fund in March.

TriMet told The Oregonian that it expects this new app to save the agency millions due to reduced transaction costs and elimination of ticket machine maintenance. GlobeSherpa also implemented a security feature on the app that allows Tri-Met officials to easily validate tickets.

Editor’s note: This story was updated to include information about Portland’s title as the first city in the U.S. to implement a mobile ticketing feature system-wide.