For the past 20 years, I’ve been taking the train to the Market East Station in my hometown of Philadelphia. But I’m not going to be doing that again anytime soon.

That’s because Market East no longer exists, at least not officially. It became Jefferson Station earlier this month, after Thomas Jefferson University Hospital paid Philadelphia’s regional transportation authority $4 million to put Jefferson’s name on the station for the next five years.

And this isn’t just a Philly thing, either. Around the country, the names of our public spaces are being sold off to private donors. Brooklyn’s busy Atlantic Avenue subway station is now the Barclays Bank station; Chicago is selling naming rights to its “L” stops; and Cleveland recently named an entire bus route “The Health Line,” after receiving $6.25 million from the Cleveland Clinic and University Hospitals.

In several other cities, meanwhile, Kentucky Fried Chicken’s logo festoons manhole covers and fire hydrants. A few municipalities have sold ads on their police cars. And seven states now allow pizza chains and other companies to advertise on school buses.

That’s good news for business, which can engage old customers and target new ones. And it’s good for our cash-strapped local and state governments, which can make long-needed improvements to crumbling infrastructures. Everyone walks away happy. Right?

Wrong. Our public spaces communicate important lessons about who we are. By selling these spaces to private interests, we teach our children — and ourselves — that nothing is truly shared; that everything is for sale, typically to the highest bidder; and that the clutter of commercial messages is the price we have to pay to sustain our common lives.

Of course, America’s urban landscape has long been littered with garish advertising. Writing in 1914, journalist Walter Lippmann bemoaned “the deceptive clamor that disfigures the scenery, covers fences, plasters the city, and blinks and winks at you through the night.” Parts of the sky were “ablaze with chewing gum,” Lippmann quipped, while the rest was “brilliant with monstrously flirtatious women.”

On the countryside, meanwhile, tobacco companies paid farmers to place ads on their barns. As automobile sales and traffic increased, America’s highways became jammed with signs and billboards for every product under the sun.