The Carnegie Library at Mount Vernon Square and the Historical Society of Washington are closed until further notice. The culprit is mold. (Jeffrey MacMillan/For The Washington Post)

Early Thursday afternoon, I went over to the Carnegie Library at Mount Vernon Square to find out about a photo exhibit set to open this week at the Historical Society of Washington. Late Thursday afternoon, I got word that the building was being closed until further notice.

Yikes! What gives? It’s that four-letter word every homeowner dreads: mold.

During environmental testing, evidence of mold was discovered in two areas in the building. Gregory A. O’Dell, president and chief executive of Events DC, the agency that oversees the building, released a statement: “Out of an abundance of caution, we are going to close the facility on a temporary basis to remediate those areas and perform testing of other spaces to ensure that the building is safe.”

This comes at a bad time. The photo exhibit — called “District II,” it features the work of Bill Barrett, Chris Earnshaw and Joseph Mills — will not open this week. (It’s unclear whether and when a new venue will be found.) And the Historical Society’s annual gala and awards ceremony, set for Oct. 7, is being relocated to the Newseum.

Then there’s the Kiplinger Library, a handsome top-floor depository of so much of the city’s past and an invaluable resource for historians, genealogists and journalists. Until the mold is gone, it’s off limits to researchers.

All of this is enough to make you wonder whether at some point in the past decade a fortunetelling crone pointed a spindly finger at the Historical Society and uttered some sort of curse. After moving in 2003 from the Heurich House Museum near Dupont Circle to the stately Carnegie Library, the Historical Society overextended itself with a D.C. city museum.

After that museum failed, the society regrouped. It had to temporarily cut back its public hours, frustrating local history buffs, but it emerged stronger and under new leadership. It has a full slate of programs — lectures, photo walks — and publishes a valuable journal, Washington History. It was one of the first organizations to help spread the word that the Smithsonian’s new National Museum of African American History and Culture was seeking artifacts for its new collection. And now this.

The priority, said John Suau, the Historical Society’s executive director, is to “ensure the safety of our staff and collections and make sure previously scheduled events can take place. We are working with community partners and will provide information as soon as possible.”

The small staff is being moved temporarily to Events DC office space in the convention center across the street.

Fortunately, the Washingtoniana collection is just down the street at the Martin Luther King Jr. Memorial Library. Of course, it’s especially important that the Carnegie Library gets cleaned up soon because MLK will close next year for a three-year renovation. The Kiplinger Library is supposed to take up some of the slack.

This is all happening just after we learned that Apple seems interested in transforming the Carnegie Library into a sort of megastore/event space. That’s fine with me — the more people who see the lovely Beaux-Arts building, the better — as long as it doesn’t harm the Historical Society, which is quite comfortable upstairs.

Suau assured me that the group’s terms with the city protect it from being tossed out.

“We will be in the Carnegie Library until the year 2098,” he said.

This is an opportunity to remind ourselves how vital organizations that collect, safeguard and disseminate local history are. They may not be first responders like police and firefighters, but they are an important part of a livable city just the same.

Road worriers

Speaking of historic, the other day I received an email from the state of Maryland about my 1968 Datsun roadster. My little red convertible wears “historic” license plates, meaning I pay less to register it and don’t need to have it smog-tested, but can’t drive it as much as a “regular” car.

The email said: “Effective Oct. 1, 2016, a Maryland registered historic vehicle may no longer be used for transportation to and from employment, school, or for commercial purposes.

“In addition, historic vehicles with a model year of 1986 or newer may be subject to safety equipment repair orders issued at roadside by law enforcement.”

Richard Liddick, president of MGs of Baltimore, a club devoted to the English marque, received the email, too. He has three MGs and an Austin American, the most recent of which is a 1977, the oldest a 1969.

Although the email came out of the blue, Richard said it wasn’t really a surprise. He suspects that people have been abusing the historic vehicle category, using vintage plates as a cheap way to keep an uninspected car on the road. “I’ve even seen utility trucks with historic plates used by handymen,” he said.

This does raise the prospect of being pulled over if a cop doesn’t think you’re on your way to a car show or a cruise-in.

“The question is what the police actually do,” Richard said. “Do they enforce it?”

A staff member of the transportation committee assured me that historic-vehicle owners may still take their cars for Sunday drives.

Twitter: @johnkelly

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