Julius Decio, an Italian-born entrepreneur, in 1951 started building mobile homes in Elkhart, Ind. Soon he turned the tiny business over to his son, Arthur J. Decio.

The son took his father’s company, later known as Skyline Corp., and ran with it. He recalled going to a trade show in New York in 1957 and meeting dealers from all over the U.S. “It was like shooting ducks in a barrel,” he told the Elkhart Truth in 2015. “You’d have to be an idiot not to sell if you had the right product.”

In 1965, he was on the cover of Time magazine with five other “millionaires under 40.” Skyline became one of the nation’s largest makers of factory-built homes and set up regional plants around the country. Just like General Motors, Mr. Decio said, his company could get its product on more dealers’ lots by offering a variety of brands.

After retiring as chief executive in 1998, he remained chairman for another decade. The company is now known as Skyline Champion Corp.

His many philanthropic roles included being a donor and trustee at the University of Notre Dame and a director of the Special Olympics. He served as chairman of the Salvation Army’s National Advisory Board.

Mr. Decio died Nov. 6 at his home in Elkhart. He was 90.

He had huge hopes for the industry. In a 1968 interview with United Press International, Mr. Decio predicted that manufactured-housing makers would within a few years account for more than half of all new U.S. homes built. “Our industry seems to be the only one in housing that can build a low-cost house and do it fast,” he said.

Other Obituaries

Sales boomed in the 1960s and early 1970s, cooled off and surged anew in the 1990s. During booms, lenders offered more credit on easier terms. As a result, home buyers defaulted in large numbers, and sales plunged. Though manufacturing quality improved, the industry struggled to shake off a down-market image.

Manufactured-housing shipments accounted for about 10% of U.S. single-family housing starts last year, down from a peak of around one-quarter in the early 1980s, according to the Manufactured Housing Institute.

Despite the industry’s troubles, Mr. Decio prospered. “I made a hell of a lot of money,” he told the Elkhart Truth in 2015. “I gave a hell of a lot away.”

Arthur Julius Decio, known as Art, was born Oct. 19, 1930, and grew up in Elkhart. His father, who emigrated from Italy as a child, worked for railroads before becoming a grocer and operating a tavern and a lake resort.

At age 8, Art Decio delivered newspapers and, according to his family, donated a third of his earnings to the Salvation Army and another third to his Roman Catholic church, where he served as an altar boy. He later attended Marmion Military Academy in Aurora, Ill., and studied economics at DePaul University.

A job offer lured him away from DePaul before he could graduate. He got more education working as a steel salesman and then took charge of his father’s fledgling manufactured-housing company.

In 1968, he was a fundraiser for Robert F. Kennedy’s presidential campaign and introduced the candidate at a rally in Elkhart. Among his close friends was Ara Parseghian, a former Notre Dame football coach, who died in 2017. They were part of a small group of men who met for lunch at an Italian restaurant each Wednesday, an event they called the Romeo club, or Retired Old Men Eating Out.

Mr. Decio is survived by a sister, five children, 14 grandchildren and 13 great-grandchildren.

His wife of 59 years, the former Patricia George, died in 2010. He carried her picture with him and showed it to everyone he met, said one of his daughters, Lindy Reilly.

Write to James R. Hagerty at bob.hagerty@wsj.com