Students from Texas on a class trip to Washington carry copies of the U.S. Constitution in their back pockets. (Sarah L. Voisin/The Washington Post)

Deep in the wheat fields of southern Idaho, the storage facility of democracy lies in wait. Seven thousand, two hundred square feet, galvanized-steel walls, and inside:

Thousands and thousands of tiny U.S. Constitutions.

The calls to the warehouse of pocket-size Constitutions come from across the country: bookstores that want to sell them, teachers who can’t afford them, politicians who will pull them out at exactly the right moment to say, “This here is my copy of the United States Constitution, that I always carry, and it says . . . ”

That trick was a favorite of the late Democratic senator Robert C. Byrd. A decade ago, Byrd was instrumental in establishing Constitution Day when he attached an amendment designating the holiday to an appropriations bill. Since then, on Sept. 17, the day the Constitution was signed in 1787, schools receiving federal funding and federal agencies must provide education about the Constitution. In D.C. and across the country, there are student-led readings, political panels, tours of the National Archives and naturalization ceremonies.

Constitution Day means swift business for Idahoan Zeldon Nelson, a farmer who spends his down time packing and shipping pocket Constitutions. Nelson sells the booklets — $1.10 a piece and wrapped with an image of George Washington — as the chief executive of a small nonprofit group called the National Center for Constitutional Studies.

Ten of the 27 grandchildren of Zeldon Nelson, CEO of the National Center for Constitutional Studies, at Nelson's warehouse in Malta, Idaho. Each pallet in the warehouse holds 21,000 pocket Constitutions that are shipped out to schools, politicians and bookstores. (Zeldon Nelson)

Since the establishment of Constitution Day, the 68-year-old has steered his organization away from its conservative roots and toward a mission of constitutional education.

Constitution Day, he says, is just one more reason to have a copy of the nation’s foundational document handy. The fact that it comes pocket-size, is affordable and is a fairly common Capitol Hill accessory speaks to the very heart of the Constitution itself.

“It’s symbolic of the very idea that the basic rules that govern the interactions of 300 million of us can be reduced to a text short enough that we could all carry it with us,” said Akhil Amar, author of “America’s Constitution: A Biography” and a professor at Yale Law School. “That we could all actually read it if we wanted to.”

And while it’s likely that most people haven’t done so since middle school, those who carry a Constitution do so with pride — and inevitably, a little bragging.

Out of the breast pockets they come, frequently leather-bound, to be lifted in the air between a thumb and a forefinger and waved back and forth for all the world to see.

During the 2012 Republican presidential primaries, Rick Santorum held his copy up at a rally at a Baptist church. Justice Stephen G. Breyer once joked that he scribbles his grocery lists in his. Rep. John A. Boehner (R-Ohio) opened up his copy and then mistakenly quoted from the Declaration of Independence instead.

Nelson doesn’t care how people use their pocket Constitutions. He just wants to get them off his farm (each pallet holds 21,000 of them) and into the hands of people who will read them. He is often helped by volunteers and his 27 grandchildren. He has no plans to retire.

“From this area of the country, we say we are going to die in the saddle!” he says.

Other purveyors of the pocket Constitution include the Government Printing Office, the libertarian-minded Cato Institute and other niche publishers.

Keir Walton, founder of ConstitutionFacts.com, has sold 5 million copies of “The U.S. Constitution & Fascinating Facts About It” since 1993. His customizable covers are popular with politicians, but his favorite customers are those who use his American-flag covered booklets creatively: pilots passing them out to airline passengers, charities sending them to military bases, even couples giving them as wedding favors.

“You can sell them everywhere,” Walton says. “Like gum!”

In the 227 years since the Constitution was printed in Colonial newspapers for land-owning white men to read and vote on, the document that can fit next to that gum has indeed changed the world.

“In 1787, the world was dominated by kings, emperors, czars, tribal chiefs and thugs,” said Amar, the constitutional scholar. “And now, half of it has democracies inspired by the American model.”

The instructions to which, as Nelson attempts to pass on from his storage unit in Idaho, can always fit in your pocket, ready to be read and shared.