When were a Congressional election and a Presidential election held at the same time?

There is always a congressional election held at the same time as the presidential election. However, since Congressmen serve for only a two-year term and the president serves for four years, there is a another Congressional election in the middle of the president's term. ( I am talking about the lower house of Congress. The senate elects one-third of its members every two years, so one-third of the senators are also elected at the same time as the President. )