Uber’s decision to bring tipping to its app is one of the most notable recent reversals of policy in tech, and now the tipping feature is actually going live in 121 cities across North America, including the biggest markets in the U.S. and Canada like New York, San Francisco, L.A., and Toronto.

When Uber announced that tipping was being added to its rider app, it went live in Seattle Minneapolis and Houston only so that the company could evaluate the experience and make tweaks as necessary. Today’s rollout expands the pool by a considerable amount, and Uber says it’s still on track to make tips available to all drivers in the U.S. by the end of this month.

For drivers, being able to accept tips requires making sure the Driver app is updated to the most recent version. If you’re on the latest build, you might also have to force quit and relaunch the app. Once it re-opens, it should present you with a screen that alerts you to the new ability to accept tips, and drivers can then click the “Accept Tips” dialog option to enable it for their riders. Tips are tracked alongside trip details for drivers.

On the rider side, tips are of course optional, and appear after you’ve rated your driver post-trip. You can retroactively tip up to 30 days following a trip, and you can choose from either one of three preset amounts, or enter your own custom tip total. Tips are also available on UberEats, and again become available after you’ve rated the driver. Customers only have 7 days to retroactively tip for past UberEATS trips, however.

Tipping is part of Uber’s “180 days of change,” which is a program it launched in June as a concentrated multi-stage effort to improve its driver experience. Some recent stats around the Uber Driver app suggest retention is down this year on the driver side, which could help explain the introduction of tipping and the continued execution of this plan.

The full list of cities where tipping begins rolling out is included below for reference: