during spring training in 2006, the nationals and orioles played each other in washington on march 31 and in baltimore on april 1. the first match-up of the regular-season beltway series rivalry took place on may 19, 2006, at robert f. kennedy memorial stadium; the orioles won. this marked first time in 35 years that the orioles played a regular-season game in washington; previously, they had played the original washington senators of the american league annually from 1954 to 1960 and the expansion washington senators – which replaced the original senators – each year from 1961 to 1971.