The first even trade between the franchises now known as the Yankees and the Red Sox happened on December 20, 1903. New York sent pitcher Jesse Tannehill to Boston in exchange for pitcher Tom Hughes. Boston got the better of that deal as Tannehill had a couple decent seasons with the team. Meanwhile, New York traded Hughes to Washington in the middle of the 1904 season after just 19 less than stellar appearances.
A month before the Highlanders traded Hughes to Washington, they had made another trade. The second ever trade between Boston and New York happened on June 17, 1904.