Millennia have passed since early man hid and hauled grain and game in primitive carriers, most likely fashioned from grasses, leaves, animal hides or tree bark.

By the 20th century, that basic need to transport food was being met by ... Hopalong Cassidy, the Jetsons and Barbie lunch boxes.

So deeply ingrained in the national psyche are these vividly branded repositories of sandwiches, cookies, apples and milk that the Smithsonian Institution is running dual lunch box exhibits. “Taking America to Lunch” opened this spring at the National Museum of American History in Washington for an indefinite engagement. “Lunch Box Memories” has been traveling the country since 2002 and is booked into 2006.

Serious collectors, who call themselves “boxers” and “paileontologists,” pay dearly for the rarest metal examples: Last year, a rectangular 1954 Superman lunch box sold for $13,225, and a rare, pristine oval 1935 Mickey Mouse lunch pail could fetch $7,000.

“It pushes so many buttons,” says David Shayt, curator of both exhibitions for the museum's cultural history division. “It's TV, it’s childhood, it’s school, it’s food, it’s mom, and it’s loss -- above all, because so many people lost theirs.” Shayt contends his own early lunch box, emblazoned with nuclear submarines and a diagram showing how one worked, inspired him to become a Marine and later a historian of technology.

To be sure, lunch boxes -- or kits or pails -- were not just for children. The iconic black metal box, with a vacuum bottle tucked in its vaulted top, has been a longtime staple of the hard-hat lunch break.

But the juvenile boxes generally captivate collectors. And for many children, they became early tribal artifacts, says Allen Woodall, owner of the Lunch Box Museum in Columbus, Ga., and co-author of The Illustrated Encyclopedia of Metal Lunch Boxes, in which he and Sean Brickell write: “They were our endorsement of something cool. And by association, we, too, informed the world we were part of a select group. With our lunch boxes, we celebrated all forms of pop culture including TV shows, cartoons, movies, comic strips, science, music acts and mythical figures.”

Like all hot collectibles, price is governed by supply, demand and condition, the last in this case being the most problematic. Lunch boxes often took a beating at the hands of their young owners. Moreover, they frequently were pitched out in June and replaced in September by models hyping the latest hit movies and pop stars.

Showing up at school with a passe lunch box was a major social blunder, says Woodall, who toted his own sandwiches in brown bags during the 1940s. By the 1970s, he eagerly paid $5 and $10 at flea markets for two lunch boxes celebrating his childhood radio heroes, Dick Tracy and the Green Hornet, and a passion was born: “I really loved the pop art on them. It was just so great.” Today he owns 2,100 lunch boxes and about 1,800 vacuum bottles, several dozen of which he has given, sold or lent to the Smithsonian.

Shayt is smitten by the broader evolutionary arc of the lunch box.

“Some of our earliest examples, from the 19th century, were woven baskets with handles. A meal would be wrapped in a handkerchief. Depending on your station, a fancy wooden box would be used by the wealthy,” he says. All these containers did the job of protecting food being taken “either to work, school, church or picnics. It was not easy to go home for lunch every day in the mid-19th century as small shops grew into large factories, and you had the need for collective schooling.”

By the 1860s, can makers had obtained patents for tins just large enough for “a hunk of meat, some bread, cheese, and maybe a pasty if it was a Welsh immigrant family,” says Shayt. “In the British Isles, men had lunch pails for going to the mines. Those were oval cylinders, stacked and tightly sealed to keep coal dust and dirt out. From British India came the stacked ‘tiffin' set. The American lunchbox quite often had a reservoir of hot coffee at the top to keep the rest of it warm.”

The trajectory of children's boxes is entirely different, he says. In the 19th century, children began carrying lunch in tins that often were highly decorative. They originally held plug tobacco, lard or biscuits and “it was a case of make do or do without,” Shayt says. By the early 20th century, the lunch kit was revolutionized by a modification of an earlier vacuum bottle constructed of double-walled glass. Its fragility was minimized once it was encased in metal. The addition of a cork stopper and screw-on cup made it the perfect vessel to keep beverages hot or cold. “The drink container came to dictate the shape of the workingman's box. It was domed, like a Quonset hut, and the Thermos bottle clipped in over top of the food,” says Shayt.

Walt Disney launched the first “character” lunch box in 1935 by putting Mickey Mouse on the lid of an oval carryall; it had an interior pie tray but no bottle. Only a handful of these tins, made for just two years by Geuder, Paeschke & Frey of Milwaukee, have survived, which may account for the $5,000 they can fetch, says Woodall.

It was television -- not movie cartoons or the funny papers -- that really drove the golden age of vivid metal lunch boxes, which spanned four decades.

In 1950-'51, TV cowboy Hopalong Cassidy, who licensed hundreds of products, granted rights to Aladdin Industries of Nashville to put his decal on the outside of blue and red lunch boxes. Inside was a beautifully lithographed vacuum bottle. More than 600,000 units galloped off the shelves. Two years later, rival cowboy Roy Rogers debuted on 2 million boxes made by the American Thermos Bottle Co.

But in the world of serious collectors, Superman reigns supreme. First depicted by ADCO Liberty in 1954 as “The World's Greatest Adventure Character” doing battle with a robot, he went on to appear on boxes produced by two other companies.

Over the next 30 years, Aladdin and Thermos dominated the market, which saw some 450 images and patterns on millions of boxes. Miss America. The Flying Nun. Pele. Rat Patrol. Davy Crockett. Howdy Doody. Mork & Mindy. Strawberry Shortcake. The Bee Gees. Care Bears. The Berenstain Bears. Star Wars. Star Trek.

The list seemed endless. But end it did, in 1985, with a gun-toting Sylvester “Rambo” Stallone having the dubious honor of gracing the last metal boxes, made by Thermos.

Some collectors blamed parents whose little darlings were injured when lunch boxes became weapons in a schoolyard brawl. An urban legend persists that the Florida legislature actually banned them in the 1970s, although no law has been found to confirm the tale.

But it was mostly a matter of economics and hygiene that gave rise to soft vinyl, hard plastic and insulated fabric lunch boxes and bags, says Shayt. “Steel was too costly. You had to roll it, stamp it, lithograph it off-site, roll the edges, put on handles and clasps.”

Such a costly process does have its upside, says Woodall. “You can't counterfeit lunch boxes. All that lithography and embossing required giant roller presses.”

Rising prices do not seem to have deterred collectors.

At least three '54 Superman lunch box sales have gone into five figures, says Bryan Los of Holyoke, Mass., a collector who runs the Web site www.lunchboxpad.com.

Last December, New Jersey physician Jeffrey Landes paid $13,225 for one in a MastroNet Inc. auction because, he says, “It's unused, in mint condition. It's like the Holy Grail.”