CLARKSBURG, Md. -- Historian James Heintze can tick off colorful accounts of how the nation has celebrated the Fourth of July over the years: In the 19th century, cannons fired, church bells sounded and fireworks exploded.

Indianapolis residents watched in 1911 as two trains purposely collided at full speed, the locomotive personnel bailing out before the crash.

The gray-haired, bespectacled academic has chronicled just about everything there is to know about commemorating the birth of the United States. His 360-page, factoid-packed book, "The Fourth of July Encyclopedia," was published last year, and he's now moved on to researching a book about Fourth-related music. He has a weighty Web site on the Fourth, making him a resource for TV shows, politicians, re-enactors and even high school students writing term papers.

Heintze, a 65-year-old retired librarian at American University in Washington, has dedicated more than a dozen years to researching the history of this single day -- a passion that began with his interest in Independence Day music. He found himself spending long days reading microfilms of articles and rare documents, at times taking verbal notes on a voice recorder in libraries that prohibited pencils and pens.

"What's fascinating about it is the hunt for treasure ... finding bits of American heritage," Heintze said.

In the study of his Clarksburg home, Heintze displays an original 1866 "Red, White and Blue Songster" pamphlet with Fourth lyrics. Heintze's otherwise calm, monotone voice gains gusto as he reads aloud excerpts from his research on parades.

He's found that the festive spirit goes way back. On Independence Day in 1778, in New Brunswick, N.J., Gen. George Washington gave his army a double allowance of rum and issued an artillery salute. In 1808, the people in Richmond, Va., decided that only U.S.-made liquor could be consumed on the Fourth. At a clam bake held in 1840 in Providence, R.I., 220 bushels of clams were eaten.

It was not uncommon for couples to get married on Independence Day. In his database of Fourth-themed popular postcards from the early 20th-century, a woman hugs a firework with these words printed on the rocket: "I will go off with you on the 4th."

Heintze notes that events on the Fourth have been tied to social and political movements. In 1827, for example, New York emancipated its slaves on the holiday. And in 1867, the Friends of Universal Suffrage met in South Salem, Mass., including Susan B. Anthony, who fought for women's voting rights.

Heintze's family has tolerated and even supported his obsession with all things Fourth. "You don't see him for days," said his wife, Yolanda, a fifth-grade U.S. history teacher who often infuses his research into her lessons. "He disappears. It's hard to find him. He forgets about sleeping, eating, everything. ... He just gets excited."

To celebrate this year's Fourth, Heintze had planned an Independence Day concert at his home. Heintze, who's played the piano since he was 4, is planning to play songs and composers whose patriotic tunes are no longer as well known, such as "Rail Road March. For the Fourth of July" from 1828 by Christopher Meineke.

He traditionally visits the National Archives and watches the Fourth of July parade in downtown Washington. This year, he also had plans to head to Richmond, Va., to hear more Fourth musical performances.

"It's a day of continued reflection," he said. "It's emotional and it's a day where I renew what I believe in."

Fourth of July Celebrations Database:

http://gurukul.american.edu/heintze/fourth.htm