NORMAN — You can find tacos in outer Mongolia, Amsterdam, Addis Ababa and Australia — even in outer space (the latter thanks to NASA). They have, in fact, become as ever present as the hamburger.

And that’s the rub. They no longer seem Mexican, but American, said Jeffrey Pilcher, a University of Minnesota history professor.

Indeed, the taco revolution spread globally — and extraterrestrially — via entrepreneurial Americans and U.S. companies, not Mexicans. That might explain why, in part, the rest of the world looks at that overstuffed hard-shell taco spilling over with lettuce, tomato and Cheddar cheese and thinks “American.”

(Not so incidentally, Mexicans migrate almost entirely to the United States, Pilcher noted. If Americans hadn’t traveled with their tacos, he said, he would be offering a very different history lesson.)

Fifty years ago, Mexican food could be found only in Mexico, California or the Southwest, including small roadside stands where tacos were sold. Los Angeles phone books from 1950 reflect the abundance of these taco spots. These were the early days of food franchises.

Glen Bell, the founder of Taco Bell and a fellow Californian, had an idea. Today we think of tacos as the lowest common denominator of Mexican food — well, maybe that would, or should, be nachos — but he was cutting-edge at a time when the rest of America was dining on tuna casserole, mac-and-cheese and cream of tomato soup.

Today foodies may sniff their noses and think “Taco Bell ruined Mexican food,” but, Pilcher said, the chain simply franchised it. As for all those arched eyebrows and comments that Tex-Mex isn’t real Mexican, well, the taco shell came out of the Mexican community — the original taco machine was patented by a Mexican — and it was adapted to local foods in the United States, as so often happens when immigrants meet the hard realities of the American supermarket.

That meant iceberg lettuce and Cheddar cheese because they were readily available.

At this point, the story diverges. California surfers and counterculture figures spread the taste of tacos throughout the world as they traveled, often in need of work. And they did what immigrants often do when they land in another country: open a restaurant.

In Amsterdam, it was a hippie with a work visa who needed to be self-supporting and started the Pacifico Cafe with tacos galore. In Queensland, Australia, the oldest Mexican restaurant — Taco Bill — was founded by another Californian who brought a tortilla press and the knowledge of how to use it.

U.S. companies added to the globalization, with Old El Paso as the leader. After all, you need the ingredients if a dish is to become popular.

By 1972, Diana Kennedy, a cooking authority on Mexican food, was pooh-poohing Tex-Mex food as not authentic.

“We forget that Texas was part of Mexico, but really it was just another region of Mexico,” Pilcher said.

In a 1980 study, Wilbur Zalinsky mapped ethnic restaurants across the United States, showing that Mexican food clearly was expanding across the nation.

Discovery of authenticity

Soon Rick Bayless, a Chicago chef and now TV cooking star on all things Mexican, and Mark Miller, a restaurateur in Santa Fe, N.M., brought serious culinary attention to Mexican food, even as fajitas began sizzling in restaurants across the United States.

Fajitas were a lower-class food in Mexico, made with lean meat from a different breed of cattle that could withstand tropical temperatures. Not marbled, the beef needed to be cooked either quickly (as in fajitas) or slowly (for molé). By the early ’70s, fajitas were served in Laredo, Texas, before the recipe headed across the country.

Then there are nachos, found in theaters in Russia or at ballgames in Anywhere, USA.

Why does this matter as we nibble on our stuffed taco?

“People will forget that tacos are Mexican just as pizza is from Italy,” said Pilcher, who specializes in food history and earned his doctorate while eating his way through Tex-Mex food in Fort Worth, Texas. He has written “Que vivan los tamales! Food and the Making of Mexican Identity.”

“The Italians brought with them all kinds of greens. Americans were not great salad eaters before,” Pilcher said. “The Mexicans brought us toma-tillos, cilantro and chiles.

“We tend to become part of that food, too.”