The postal service suffered a net loss of $9 billion last year.
Nearly 150 people from 23 countries have been stranded at sea on the MV Hondius cruise ship after an outbreak of hantavirus.
Officials estimate that fraudsters steal up to $300 billion annually from various government programs.
Celebrations include a large-scale Mall festival, a tall ship gathering, and programs across multiple states.

The lawsuit raises issue with a state law and a city ordinance designed to limit local cooperation with federal immigration enforcement activities.
A Faint Meow in the Rubble of a Mississippi Tornado Leads to a Stunning Rescue.
Nebraska’s formula for issuing electoral votes means every district counts. This isn’t a presidential election year, but Democrats aim to win District 2.
Terrorists and a priest convicted of sexually assaulting a child are also on the Justice Department’s list.
The report shows that nearly 80 percent of new homes for sale are located in suburban areas, compared with more than 55 percent of existing homes.

A federal probe has been launched as state lawmakers and agencies continue efforts to fraud-proof government programs, amid new reports raising suspicions.
Under the proposed legislation, any land purchase by a foreign adversary near a sensitive U.S. site is a national security threat.
The ceasefire will start May 9 and last until May 11, the president said.
Long-discussed files including footage of Unidentified Flying Objects and flying discs, documented between June 1947 and July 1968, were released on Friday.
Shut out of the U.S. market, Chinese automakers are investing in Mexico, exploring Canada and designing EVs that match North American consumer preferences.
The court found that the tariffs were not allowed under a 1974 trade law.
Cameras and reporters were not allowed in the Oval Office during the meeting between the two leaders.
The seizures come as U.S. forces intensify strikes against narco-trafficking vessels linked to designated terrorist organizations overseas.
The new strategy document lists cartels and violent left-wing groups, alongside Islamic extremists, as the three major terror threat categories.
U.S. Department of Justice files second lawsuit over gun laws in Colorado, saying the bans violate the Second Amendment.
With substantial reduction in use, researchers found little or no impact on test scores, attendance, and engagement in class.