A social media scandal erupted in a small Mississippi town on Friday night, ahead of the Martin Luther King Day federal holiday.

In a since-deleted tweet, the city of Biloxi said some municipal offices would be closed on Monday “in observance of Great Americans Day, a state-named holiday”.

Residents, shocked that the city had changed the name of the federal holiday designated in honor of civil rights leader Martin Luther King Jr to celebrate “Great Americans”, quickly voiced their complaints.

@CityofBiloxi Umm... this Biloxi resident celebrates MLK Day. — Annie (@futuristicplans) January 14, 2017

The city was quick to say that it did recognize Martin Luther King Day and had posted details of the celebrations planned in honor of King.

The incident, however, highlighted an awkward truth about Mississippi’s Martin Luther King Jr Day: that it is also Robert E Lee Day.

Lee was a leading commander of the military forces of the Confederacy, which fought in defense of slavery in the civil war from 1861 to 1865.

Arkansas and Alabama also jointly celebrate Martin Luther King Day and Robert E Lee Day, despite annual protests.

People pushed for a holiday commemorating King immediately after he was assassinated in 1968. Congress eventually recognized their efforts, and the third Monday of January was first observed in King’s honor as a federal holiday in 1986.

But some states and municipalities were slow to recognize the federal distinction: New Hampshire was the last state to officially observe the day, in 2000.

The same year, Virginia stopped its annual recognition of Lee-Jackson-King Day, which celebrated Lee and King as well as Confederate general Stonewall Jackson.

Biloxi city officials found themselves beginning the Martin Luther King Day weekend of 2017 with a social media backlash.

Mayor Andrew “FoFo” Gilich said that when workers return on Tuesday, the city council should move to update its laws to reflect the federal name of the holiday.

“In my opinion,” he said, “that is the appropriate step to take, for the holiday to have the same name as the federal holiday.”

He continued: “We’ve always celebrated this day as Dr Martin Luther King Jr Day.”

Biloxi’s local newspaper, the Sun Herald, said there was no evidence of “Great Americans Day” in media databases covering the past 20 years or in the Mississippi secretary of state’s office.

Under pressure to explain the social media posts, Biloxi public affairs manager Vincent Creel found that the city had created the “Great Americans” designation in a 1985 city council meeting.

“For whatever reason, the state couldn’t bring itself to just say ‘Martin Luther King Jr Day’,” Creel told the Huffington Post, in reference to the state’s inclusion of Lee in the holiday.

“Somewhere along the lines, that evolved into ‘Great Americans Day’, unfortunately. And yes, I did say ‘unfortunately’.”