The question is, once you start sifting through those boxes, how do you know what's worth keeping — or for that matter, selling?
Hands down, George Washington and Abraham Lincoln relics will always be something to celebrate, but often the memorabilia market is determined by who really mattered in 20th-century politics. The shoes of Gerald Ford, an 895-day president who was never actually elected, or the cowboy hat of Ronald Reagan, the two-term president who was a movie star? No contest.
In any collecting field, rarity and good condition raise the value. At the top of the market, Washington's personal copy of the Constitution and Bill of Rights, bound in leather, sold last week at Christie's in New York for $9.8 million, a new world auction record for an American book or historical document.
The first president not only signed the title page, but he had annotated the documents in pencil. The unique lot came from the estate of noted Chester Springs collector H. Richard Dietrich Jr., who died in 2007.
Until 1876, the bound volume had been in the library at Mount Vernon. The winning bidder was a representative of Washington's historic home, so the precious artifact will be heading back to Virginia.
Maybe you might find a Lincoln commission. According to David Bloom, vice president at Freeman's, "During the Civil War, Lincoln actually had to sign every officer's commission."
Even though they come to auction frequently — usually cause for a lower estimate — Lincoln is so beloved that those commissions usually do well, "depending on how attractive the signature and the document are," said Bloom. Freeman's sold one of these commissions in September 2010 for $4,375.
Upping the ante considerably, a signed photograph of Lincoln brought $85,000 earlier the same year, well beyond its $8,000 to $12,000 estimate. Adding to its value was that the carte-de-visite image shows him standing, when he appears seated in most photographs.
The context can matter too: One lithograph by the popular New York-based Currier & Ives printmaking firm that Freeman's has sold several times documents the Republican presidential nomination in 1860, featuring Lincoln.
"It captures a historical moment, when he was just another candidate, before he became one of our most beloved presidents," Bloom said. These prints sell for between $300 and $500, depending on their condition.
Interestingly, sometimes documents from recent presidents can be worth more than their predecessors. That's because back in the days before secretaries and computers, presidents were doing more of the signing and documenting.
"So when you find significant material in Kennedy's or Reagan's hand, they will do very well," Bloom said.
Last year, Freeman's sold items from the estate of Maj. Gen. Chester V. Clifton Jr., a military aide to Presidents John F. Kennedy and Lyndon Johnson. A document relating to Polaris submarines signed by Kennedy brought $4,375, while bound copies of the president's daily schedule sold for $7,500.
Among the postwar presidents, Reagan — still with a wide personal following — is very collectible, said Slater.
Politics and political collecting are a national game, and certain auction houses are famous for specializing in the best material, like Heritage, based in Dallas with branches in Beverly Hills and New York.
Slater tells an amazing story of an 1860 political advertising flag for John C. Breckinridge, the Southern Democratic candidate who ran against Lincoln — found under the floorboards of a Philadelphia house.
"Actually it was the only one known, one of those things that everyone thought probably had existed but had never appeared," Slater said. It brought $95,600 in 2009.
The political expertise of Heritage attracts consignments directly from political families. This spring the firm hosted an auction from the Johnson family. The sale would benefit the Lady Bird Johnson Wildflower Center at the University of Texas.
If you uncover political memorabilia, Freeman's and Heritage are good resources. Take quality digital images, note condition, and gather family history about the object.
Be willing to accept an expert opinion; specialists know what will sell. Some objects may be more appropriate for eBay than the auction block, but it is always worth finding out.
Although political memorabilia collecting may seem like a boys' club — guys collecting material signed or owned by other guys — the market changes with the players. Margaret Thatcher material has a wide fan base in England, and you can bet that anything connected with a future female U.S. president will be avidly sought.