WASHINGTON—In an effort to reach out to a previously untapped customer base, the struggling United States Postal Service announced Tuesday that it would extend its business hours to 3 a.m. to meet America's late-night mailing demands.

"People's lives don't stop at five o'clock, and neither do their shipping needs," said Postmaster General John E. Potter, addressing reporters during a rare early evening press conference. "Starting this week, the post office will extend its hours well into the night. Now, millions of Americans who enjoy our nation's exciting nightlife will no longer have to wait until the sun comes up to mail that important package to a loved one, old school mate, or Michael Jordan."

Added Potter, "The mail just got a lot more fun."

The move comes after a trial run of the extended hours in six urban markets, where post offices saw a 137 percent spike in overall revenue—most of which was conducted in the 15 minutes after last call. There was also a threefold spike in passport applications, largely the result of drunken individuals stumbling in at 2 a.m. and making spur-of-the-moment plans for a road trip to Mexico.

Potter also unveiled a new campaign to promote the program, which the government agency is calling "USPS P.M." In a TV ad screened for reporters, the eagle from the USPS logo is seen morphing into a night owl, who then swoops by a group of young people exiting a chic nightclub and says: "Closing time—you can go to the post office, but you can't stay here."

"We're busier than ever, though to be honest, a lot of these people's packages never even make it to the processing center," Loftus continued. "The address will be illegible, or the envelope soaked in beer or hot sauce. You'd be surprised how many people try to mail themselves hot sauce at 2:30 in the morning."

As part of its promotional efforts, the USPS will commemorate the nation's 10 most popular microwavable snack foods with a limited- edition series of stamps, which, along with cigarettes, will be available at wildly inflated prices in packs of 20 from lobby vending machines.

According to post office insiders, the program has enjoyed great popularity thus far, in part because it allows patrons to fulfill their drunken communication impulses without having to deal with the repercussions for days or even weeks.

"No one I know mails anything before 1 a.m. anymore," Darrick Routledge, 24, said while entering a post office in Chicago's trendy Wicker Park neighborhood. "What's the point?"

In a recent poll of after-hours post office patrons, 65 percent of respondents were attempting to mail angry letters to their ex-girlfriend or boyfriend, 30 percent were wearing Priority Mail envelopes as hats, and the remaining 5 percent wanted to know what the fuck the pollster was looking at.

"My shoes started hurting, so I mailed them to Foot Locker," New Orleans patron Patrick Balmer said. "I said it, right in the letter, I said, 'You fuckers deal with it!' Not my problem anymore."

"Thanks UPS PS P.M.!" added Balmer, using a customs declaration form to stanch the flow of blood from his big toe.

While the program has been an economic boon, it has also created its share of problems: Bouncers have been brought in to deal with violence at several of the participating branches, and complaints of overflowing mailboxes have been voiced by residents of the small northeastern port town of Fuck, ME.

"Last night I had to stop a guy from climbing behind the counter to check for his Netflix arrivals," Las Vegas postal security guard Darius Whitman said. "And people get angry when they wait half an hour in the package-pickup line and then find out there's no bottle service. Sometimes it's rowdy, but mostly it's just people laughing, making out, mailing off Bacon of the Month Club orders, and having a good time."

"That's what people come to the post office for," Whitman added.