Ralph Whittington worked at the Library of Congress for 36 years, rising from an entry-level clerk to become a curator in the main reading room of the library’s majestic building across from the U.S. Capitol.

He supervised the library’s collection of telephone books — “I was in charge of every phone book in the freaking world,” he said in 2002 — and also used his expertise as an archivist in his private life. Mr. Whittington had more than 5,000 early recordings of rhythm-and-blues and doo-wop music, but he was better known for amassing one of the world’s largest collections of pornography.

For years, he stored his trove — which included thousands of items, from 19th-century “bawdy house coins” to magazines, videotapes, photographs, dolls and devices — at his Clinton, Md., home, which he shared with his mother.

Mr. Whittington, who was 74, died at his home on Aug. 6. The cause was cardiovascular disease, said his son-in-law, Stephen Chittenden.

For Mr. Whittington, his collection was neither a hobby nor a shameful indulgence stored at the back of a closet. It was a serious academic undertaking; his interest was curatorial, not prurient.

Pornography is a multibillion-dollar industry and has been part of human history for millennia, but serious study of the subject has been haphazard at best. Mr. Whittington sought to fill that gap by keeping a systematic record of the artifacts that define the myriad desires of the human libido.

“I really enjoy this stuff,” he told the Washington City Paper in 1997. “I’m not like some guy who says, ‘I only read Playboy for the articles.’ I mean, I really do take a hands-on approach.”

Notable deaths in 2019: Elijah Cummings, Cokie Roberts, Toni Morrison and others we have lost this year

Don Imus | Don Imus, who spent more than half a century in radio and television skating along the edge of propriety and occasionally falling into the abyss of the unacceptable, died Dec. 27 at a hospital in College Station, Tex. He was 79. In a roller-coaster career in which he grew chummy with prominent politicians, repeatedly got suspended or fired for offensive cracks, abused drugs and touted health foods, Mr. Imus won a loyal following, made millions and transformed himself from a bad-boy DJ into a host whose program became a nearly mandatory stop for presidential candidates. Read the obituary (Richard Drew/AP)

On his business card, Mr. Whittington listed his occupation as “erotic archivist.” When discussing pornography, he did not apologize, stammer or blush. He documented his items with the same rigor that he used at the Library of Congress.

Everything was catalogued and cross-referenced. Boxes were carefully labeled with the name of a porn star or a thumbnail description of the infinite variety of carnal proclivities depicted in print or on film. Mr. Whittington noted 86 separate categories.

“The key is the diversity of the collection,” he told The Washington Post in 2002. “To be blunt, most people buy for their own gratification. But I would spend money on stuff I didn’t even like. I like high heels and big legs, but I collected everything — except gay porn and child porn.”

Mr. Whittington spent more than $100,000 on his collection and often accepted donations from heirs surprised by unexpected discoveries in the attic.

“About every six months I’ll get a call out of the blue,” he told the website gettingit.com in 2000. “Usually somebody’s uncle Charlie died and the family were going through his stuff and found his porno. They can’t put it in a rummage sale, and they know that I’m going to keep it.”

Mr. Whittington’s dedication to his field was comprehensive.

“I have bawdy house coins from whorehouses in the 1860s,” he told gettingit.com. “One coin says, ‘10 cents for lookie, 25 cents for feelie, 50 cents for doie.’ I have one film from 1913 called ‘Free Ride,’ which is supposed to be [the] oldest film they’ve found in the U.S.”

He had a copy of the first commercial sex videotape sold to the general public, a version of “Deep Throat” playable only on an obsolete Betamax machine. Mr. Whittington had a Betamax player, of course, but one piece of equipment he never owned was a computer. As a result, his expertise remained rooted in the era before magazines and videotapes gave way to the Internet.

In a short 1996 documentary, Washington filmmaker Jeff Krulik dubbed Mr. Whittington the “King of Porn” — a sobriquet he relished, but only up to a point. As an expert on the subject, Mr. Whittington had to admit that the title had previously been bestowed on actors John Holmes and Ron Jeremy.

In 1999, Mr. Whittington sold most of his materials to the Museum of Sex, a professionally curated institution in New York. Before three 16-foot trucks hauled away almost 10,000 items in 848 boxes, his house was packed from floor to ceiling. Videotapes shared space in the pantry next to cereal boxes, and sex tapes were stacked in his mother’s closet.

May Whittington was philosophical about her son’s avocation. In a 1999 episode of Jon Stewart’s “The Daily Show,” she contentedly crocheted on the couch as her son discussed his collection.

“It’s something he loves,” she told The Post in 2002. “You see men his age going to bars or on dope. But he’s home day and night. That gives me peace of mind. . . . He’s not doing anybody any harm, and he’s not doing himself any harm.”

Ralph Edward Whittington was born Jan. 13, 1945, in Washington and grew up in Clinton. His father worked for Pepco, and his mother was a homemaker and a volunteer with the fire department auxiliary.

Mr. Whittington recalled that his first encounter with pornography came during a second-grade field trip to Baltimore, where he found a book of smutty pictures on a park bench.

After graduating from Surrattsville High School, Mr. Whittington joined the Library of Congress, his sole employer until his retirement in 2000.

Mr. Whittington, who sometimes appeared on radio programs as an authority on R&B music, donated his record collection to the Library of Congress. He also had an extensive knowledge of automobiles and Washington-area high school sports.

His marriage to Jennifer Rutland ended in divorce. (His archival interest had nothing to do with the breakup, his daughter said.) After the divorce, Mr. Whittington invited his widowed mother to share his house. She lived upstairs, and he stayed in the basement, where he kept the bulk of his collection. May Whittington died in 2013.

Survivors include a daughter, Amanda Chittenden of Gambrills, Md.; and a grandson.

Mr. Whittington, who was a consultant to the Erotic Heritage Museum in Las Vegas and the now-defunct Institute for the Advanced Study of Human Sexuality in San Francisco, sometimes mocked academics as people who “will read nine books on brothels and write the 10th one and never go to a brothel.”

He sometimes conducted his research in person, including one instance in which he appeared on camera. For a fee, an adult-film star named Chessie Moore offered members of her fan club the opportunity to make an explicit videotape with her.

As Moore’s husband ran the camera, Mr. Whittington directed and took part in the action. Moore later autographed her spike-heel pumps, which Mr. Whittington added to his collection.

Even after selling many of his materials in 1999, Mr. Whittington couldn’t stop acquiring, and his house began to fill up again. He didn’t allow anyone to borrow his artifacts, but he invited visiting scholars and the merely curious to view them from time to time.

“When people come here, at least I don’t bore them,” he said. “They may leave shaking their heads, but they’re not bored.”