EL DORADO, Ark. — In one of the most generous programs of its kind anywhere in the country, an oil company announced yesterday that it is putting up $50 million for college scholarships for nearly all high school graduates in its working-class hometown over the next 20 years.

Students at an El Dorado High School assembly screamed and applauded when Murphy Oil, the nation’s ninth-largest refiner, unveiled the program. Some wept, and one made the sign of the cross.

“I wasn’t sure if I’d be able to get everything paid for with all the loans I’d have to get,” said Scott Zimmerebner, a senior. He said plans to attend the University of Arkansas in Fayetteville. “Now, that it’s all paid for.”

Murphy Oil said it wants to increase the number of students who attend college and perhaps attract new businesses to El Dorado, with the scholarships a selling point. It said it also hopes the program will help create better jobs here for students to come back to after graduating from college.

The program begins with this spring’s graduating class. El Dorado High, the sole high school in town, has about 250 graduates each year, about 65% of whom go to college.

Under the El Dorado Promise program, students can use the scholarship money at an Arkansas institution or at any out-of-state college. But the annual scholarships are capped at the highest resident tuition rate at an Arkansas public university, currently $6,010.

Students who attended school in El Dorado since kindergarten are eligible for the full amount; students who attended for all four years of high school get 65%. Those who have been in the district for less than four years are ineligible.

A similar initiative began last year in Kalamazoo, Mich., but the city’s graduates must elect to attend a public university in Michigan. The program began with an undisclosed amount of money from an anonymous benefactor.

“This is a huge day. As of today, El Dorado High School graduates will have an unprecedented opportunity to continue their education,” Superintendent Bob Watson said.

“For some students, this is life-changing. Students who have worked hard but would not have been able to attend college because of financial limitations now have the means to do so.”

Murphy Oil will put up $5 million a year for 10 years to fund the El Dorado program, which is expected to last 20 years.

“We are committed to making El Dorado a great place to live and work, and we created the promise to further invest in El Dorado’s greatest resource, our children,” said Claiborne Deming, Murphy Oil’s president and chief executive.

El Dorado (pronounced el duh-RAY-doh), a city of 20,500 about 120 miles south of Little Rock, is in Arkansas’s oil-and-gas producing region. Many people in surrounding Union County have jobs in logging. The county’s per-capita income is just under $32,000 — just shy of the state average — and fewer than one in five residents live in poverty. Fewer than 15% of Union County’s residents have college diplomas.