The first president to leave the US while in office?

Theodore Roosevelt was the first sitting president to leave the country. He visited Panama while he was president. He and wife left for Panama on November 9, 1906 on the yacht Mayflower and then transferred to a battleship, the Louisiana, convoyed by two armored cruisers , the Washington and Tennessee.

The purpose was to spend four days inspecting the construction of the Panama Canal. He then went to Puerto Rico, spent one day in San Juan, and returned to Washington on November 27. The ship was equipped with a wireless telegraph