To protect and promote the American merchant marine by shipping United States mail exclusively aboard United States-flag vessels.

[AI summary unavailable — showing source text] Amends the Merchant Marine Act, 1936 to require the Postal Service to contract with U.S. registered vessels for international sea transportation of mail. Requires rate charges for such transportation to comply with the Shipping Act of 1984. Authorizes competitive bidding for such contracts and limits such contracts to a one-year duration. Prohibits the Postal Service from contracting with vessels based on cargo container size, unless necessary.…