[2] On December 3, 1978, U4 went through a minor rerouting change to divert into/serve the newly opened Minnesota Avenue station.

On January 22, 1984, route U4 was rerouted to operate between Sheriff Road and Capitol View passing Minnesota Avenue station in both directions.

[4] In 2014, WMATA announced a series of proposals for route U4 that will be implemented in June 2015 if it was approved by the Metro Board.

It went as the following:[5] This rerouting was to create a better balance of capacity and demand on lines serving the Minnesota Avenue station.

During the COVID-19 pandemic, Route U4 was reduced to operate on its Saturday supplemental schedule during the weekdays beginning on March 16, 2020.