Informants were interviewed in log cabins and sod houses, on porches and in bars, while they were ironing or hanging tobacco to dry or, as in the case of a police officer in South Boston, directing traffic. Some were reluctant to admit using a regional dialect at all. “I try to keep my speech in the Cadillac,” a 73-year-old housewife in Astoria, Ore., told David Goldberg, a fieldworker from New York City.

Others had darker suspicions about just what a bunch of college kids driving around in vans painted with the logo of the University of Wisconsin were really up to. At a picnic ground in western Kentucky in 1969, Sharon Huizenga, a fieldworker, overheard a group of men talking about campus protesters, asking, “Why didn’t they just kill a few?”

“I thought, ‘I’m one of them,’ ” Ms. Huizenga recalled in a telephone interview. “There were times I feared for my safety.”

Back in Madison, it took five years to enter on computer punch cards some 2.3 million answers provided by 2,777 people, then 10 more years to produce Volume I, published in 1985. (The editors also drew on data from previous dialect surveys, as well as examples from books, newspapers, diaries and letters, much of it combed through by a network of volunteer readers.) The next three volumes appeared at roughly five-year intervals.

The final volume took 10 years, less because of the complexities of entries like “youse,” “you-uns” and “y’all” — “Pronouns are hard,” Ms. Hall said — than the daunting task of sorting through the flood of newly available digital sources.

Over the years DARE has been consulted by Broadway dialect coaches, detectives analyzing ransom notes, scholars puzzling over a Eudora Welty reference to “piecing” (that is, snacking) and poets looking to mine its 170-plus synonyms for dust bunnies — otherwise known as curds, fooskies, ghost manure, gollywogs, reebolees and “somebody either comin’ or goin.’ ”