The sandwich has always held an important place in the American diet. Yet what sits between the bread slices depends on where the sandwich is made and eventually eaten. The sandwich of your childhood reveals not just your culinary roots but your hometown.

In our corner of the United States, visitors might be surprised to see chow mein sandwiches. Crunchy Asian-style noodles mixed with a saucy blend of celery, onions and bean sprouts and served on a hamburger bun is not a common sandwich. But it offers a taste of home for those who live in Rhode Island and Southeastern Massachusetts, including its birthplace of Fall River.

I know because I just read it in a book.

Jane and Michael Stern have made a career of writing about what they call “roadfood” but what most of us think of as comfort food. They tell the stories of America through visits to the multitude of small diners and joints from one corner of the country to the other. “You are what you eat” in their stories of the quirky regional differences they find while driving from town to town. They favor homestyle spots, greasy spoons some might say, not fine-dining establishments.

Now they have come to the subject of Roadfood Sandwiches (Houghton Mifflin, $14.95), exploring the favorites of Americans from coast to coast. Looking through its 240-plus pages, I searched to find Rhody’s contribution and there it was on page 48 — chow mein.

The Sterns give due credit to Fall River’s Oriental Chow Mein Co. and its proprietor Frederick Wong, who started making crunchy noodles when he opened his business back in 1936. A gravy mix followed, and chow mein took off as an inexpensive and tasty meal and perfect for take-out. As the factory flourished, the sandwich was served everywhere from home to schools to restaurants. The versions might differ with some having meat mixed in, but the crunchy noodle in a sauce was the defining characteristic.

More than 70 years later, Oriental Chow Mein Co. still sells those crunchy chow mein noodles, in markets under the brand name Hoo-Mee. Both the noodles and the gravy mix are available at the factory store at 42 8th St. in Fall River (508) 675-7711. You can even buy both on the Internet at www.famousfoods.com , a New Bedford-based company.

The Sterns wrote this about the sandwich: “It is certainly not a sandwich you can pick up and eat, and while a bun floating in chow mein at first seems anomalous, the eater soon discovers that it is a mighty handy tool for mopping up the last of the gravy from the plate.”

The sandwich has tickled the interest of others. A few years ago a Canadian college professor from British Columbia asked Journal readers to keep her abreast of restaurants that continue to serve chow mein sandwiches. She taught a food and culture course and was fascinated by its popularity, which she felt waned after the 1960s.

She’d be happy to hear it’s still served in the area at many Chinese restaurants, but at some unexpected spots as well. That would include in Tiverton at Evelyn’s Drive-In, 2335 Main Rd. Owner Domenic Bitto said that although they used to offer the sandwich only Monday through Thursday, it’s again on the menu every day. The cost is $3.99, but its legacy is priceless.

gciampa@projo.com