WASHINGTON — The U.S. Postal Service has reduced its volume of shipments by aircraft by 90% over two years, putting the service on course to save $1 billion in annual transportation costs.

This week, mail enthusiasts, horseback riders and onlookers are celebrating the Pony Express’ 163rd anniversary with a nearly 2,000-mile trek from Old Sacramento, Calif., to St. Joseph, Mo.

Rates for Priority Mail packages shipped via the U.S. Postal Service will go up on average 9.8% on Jan. 17, a move that comes at the same time that private delivery services are also raising rates.

Fiat Chrysler said it will supply more than 9,000 customized cargo vans to the U.S. Postal Service for delivering mail and packages.

The U.S. Postal Service reported a net loss of $586 million for its third quarter of fiscal 2015, a reduction of $1.4 billion from the net loss of $2 billion for same period last year.

Raising the U.S. gasoline tax is out as a way to shore up the Highway Trust Fund. So is taxing drivers based on the number of miles they clock. A plan to use taxes on companies’ overseas profits hasn’t gone anywhere.

The U.S. Postal Service will end a same-day delivery experiment in San Francisco on March 1 after it could not find enough retailers to participate, Bloomberg News reported.

The U.S. Postal Service said it plans to increase overall prices 2.4% in 2014.

The financially strapped U.S. Postal Service wants to raise the price of a first-class stamp to 49 cents, Bloomberg News reported.