A flashing sign at the Tackett’s Mill commuter lot in Northern Virginia cycled through a trio of messages about the presidential election, including two that were disparaging to the Democratic nominee. (Kenneth Acoff Jr.)

Authorities are investigating apparent tampering with an electronic road sign at a busy Virginia commuter lot that resulted in a disparaging remark about Democratic presidential candidate Hillary Clinton and a call for people to “Vote Trump.”

The sign at the Tackett’s Mill commuter lot in Lake Ridge flashed three consecutive message screens: “CROOKED ­HILARY”; followed by a profanity (“IS A B - - - - ”); followed by “VOTE TRUMP.”

The messages were on display for an unknown period Tuesday evening while commuters headed to their homes in the Virginia suburb, about 25 miles southeast of the District.

Their tone reflects the bitter 2016 presidential race, in which both major-party candidates are historically unpopular and Trump’s supporters openly wear T-shirts calling Clinton the b-word and gleefully chant “Lock her up” during his rallies.

[Post-ABC poll finds race tied as Trump opens an 8-point lead on honesty]

After the sign that had been tampered with was reported, it was turned off and the equipment was removed, according the Prince William County police. (Kenneth Acoff Jr.)

“Crooked Hillary” is a name Trump coined for Clinton and uses regularly. Earlier this week, a tweet from the account of Texas’s agriculture commissioner, a Trump adviser, took the name-calling a step further, using a vulgar term for female genitalia to refer to Clinton.

In Prince William County, the offending electronic sign was one that had been placed in the commuter lot about a month ago by the county elections office. It was programmed to broadcast a message encouraging early voting for those who cannot make it to the polls on Tuesday.

There are about 10 such signs posted in heavily trafficked areas across Prince William County, a relative Republican stronghold in the Washington area. The Board of County Supervisors is chaired by Corey Stewart (R), a high-profile cheerleader for Trump who co-chaired the GOP nominee’s Virginia campaign until a dispute last month led to his ouster.

Election officials in the county, which also has a fast-growing Latino population, are taking special measures this year to speed voting and minimize potential disruptions at the polls.

[Polling stations will have extra staff, training to maintain order ]

On Wednesday, officials said the tampered-with sign equipment had not been locked, giving whoever changed the message easy access to a keyboard panel inside.

“There’s a set of instructions next to the panel,” said Winston Forrest, a spokesman for the county elections office. “Anyone who could get access to it could make the change.”

Speaking in Melbourne, Fla., Sept. 27, Republican presidential nominee Donald Trump called his Democratic opponent Hillary Clinton a “crooked woman.” (The Washington Post)

After the errant message was reported, it was turned off and the equipment was removed, according the county police.

County elections officials said they have placed locks on the remaining voting road signs in the county. “There are no more of these types of messages,” Forrest said.

The Tackett’s Mill lot sits off Old Bridge Road, near the Tackett’s Mill Center shopping plaza that marks the site of Prince William County’s original town center, according to the center’s website.

With about 860 parking spaces, the lot is a drop-off site for commuters using the Potomac and Rappahannock Transit Commission’s OmniRide bus line connecting Lake Ridge and Washington. It’s also used as an informal spot for “slugging,” where strangers meet and agree to carpool to work together.

Kenneth Acoff Jr., a travel planner and consultant who lives in Woodbridge, said he was slugging Tuesday and was dropped off at the lot just before 6 p.m. As he waited for his wife to pick him up, Acoff saw the sign flashing its message.

“When I turned around, as I left the car, I noticed this message flashing in front of me,” Acoff said. “I was shocked and appalled that this message was on public display like that.”

Acoff said that he and about eight other commuters tried to delete the message but were unsuccessful.

A woman then simply turned off the sign. Police arrived a short time later to take the sign away.

“Regardless of who you support, it’s uncalled for to engage in that type of behavior,” said Acoff, who said he cast an early ballot for Clinton. “I have young children, and that parking lot is on a very busy thoroughfare.”