Perhaps if this were not Presidents’ Day weekend, it would have been easier to ignore what happened Sunday night at the Washington Monument.

But on the middle day of the long weekend many associate primarily with George Washington, the lights did not go on at the monument named for America’s first president.

The floodlights that illuminate the 555-foot-tall stone obelisk and add a dimension of nighttime visibility to what is already one of the foremost symbols of the District and the United States did not bathe the shaft in their bright glow.

Mike Litterst, a spokesman for the National Park Service, said the lights failed to turn on as scheduled at about dusk. He said Park Service electricians were called, and at about 7:20 p.m. the lights were on as usual.

The cause of the outage was not immediately known.

It was the third time this year the lights at the monument failed to do their job. It seemed to add one more indignity to the history of troubles that have plagued the monument since it was damaged in the August 2011 earthquake that was felt up and down the East Coast.

The next year brought an announcement that the monument would be closed for repairs until 2014.

But in recent years, one problem after another impeded operation of the elevator inside the monument, which opened to the public almost 129 years ago.

The elevator, a vital part of the tourist experience, carried visitors from the ground to a lofty observation level that offers a panorama of Washington.

The interior stairs have long been closed to the public. Without the elevator, the monument could scarcely operate as the tourist attraction it has been.

Authorities finally decided to close the monument once more to modernize the heavily used elevator.

But even closed, the monument plays a symbolic role. For the countless thousands who do not contemplate a trip to the top, it has nevertheless served as a luminous sentinel, signifying calm and continuity in the Washington night.