The U.S. Postal Service will start providing mail service to Cuba on March 17.

The move marks the first time in more than 50 years that U.S. citizens are able to send direct mail to the island nation.

"The U.S. Postal Service is pleased to participate in the historic direct transportation of mail service with Cuba," Postmaster General Megan J. Brennan said, in a statement. "Moving letter mail and package volume directly between our countries will improve service for businesses and consumers."

USPS said customers can send "First-Class Mail International items, such as postcards and letter size envelopes, First-Class Package International Service items, Priority Mail International Flat Rate envelopes and Priority Mail International Small Flat Rate priced boxes" to Cuba.

There are requirements for shipping humanitarian gifts. The USPS's country conditions for shipping to Cuba can be found here.

The move is another step in a continuing thaw in diplomatic relations between the Cold War rivals that began in 2014.