The Amazon-U.S. Postal Service deal for Sunday deliveries puts the innovations of the new together with the established network of the old. It could help them both, as well as solve a practical problem for millions of Americans.

The agreement announced last week will affect only the New York and Los Angeles metropolitan areas this holiday season, with planned expansion the following year in Dallas, Houston, New Orleans and Phoenix.

But the impact could be felt nationwide. For starters, if you’re buying from Amazon for a working friend or relative in those areas, their window of opportunity to be home to receive the delivery just doubled. In Bend, you might not worry about a package being left on your doorstep while you’re at work, but that doesn’t apply in the big city. So the customer gain is obvious.

The bigger potential, though, is that Amazon and USPS have a lot to gain from each other, and we could all be the beneficiaries.

The Postal Service’s troubles are well-known, with big losses from declining first-class delivery and congressionally imposed restrictions. But its package delivery has been a bright spot, and moving into Sunday delivery — which its competitors don’t do — could enhance that strength. For Amazon, use of the Postal Service’s extensive infrastructure could advance its growing efforts to deliver goods fast to just about everywhere.

The Postal Service has long been hobbled by restrictions. Over the years, competitors have innovated, taking away much of the lucrative package delivery business, while USPS was left with requirements to serve rural areas and maintain six-days-a-week delivery. We favor continued service to small towns — it’s critical for far-flung communities — but other restrictions have left the Postal Service at a disadvantage. Teaming up with one of the top innovative companies could be a turning point that will help USPS serve and thrive at the same time.