Bill France Jr., who transformed NASCAR from a regional American auto racing circuit into a billion-dollar conglomerate during his 31 years as chairman, died yesterday at his home in Daytona Beach, Fla. He was 74.

A shrewd businessman and protective of his family-owned company, France often riled car owners, drivers, sponsors and fans.

He became chairman in 1972 when he replaced his father, William Henry Getty France, who founded the National Association for Stock Car Auto Racing in 1947.

Bill France prepared for the job by doing a little bit of everything during his rise through the grass roots ranks of racing, even helping in the construction of Daytona International Speedway. He inherited a circuit steeped in the tradition of the Southeast.

Over the span of three decades, France oversaw the expansion of the sport, parlaying the fan base of the Deep South into sold-out tracks in New England, California, Texas, and the Midwest. He also moved the season-ending awards banquet to New York City in an effort to court the Madison Avenue money.

Before France’s tenure began, the few races that did make it onto TV were only shown in snippets on shows such as ABC’s “Wide World of Sports.” But within six years, France had a deal with CBS Sports to televise the 1979 Daytona 500 from flag to flag.

In 1999, NASCAR finally packaged the entire circuit together in a $2.4 billion contract that awarded races to the Fox and NBC television networks and TNT cable.

France’s last public appearance was February 12 in Daytona Beach, where NASCAR’s top names gathered to “Roast and Toast” him at the Bill France Hot Dog Dinner during the Daytona 500 build-up.

Officials at Dover International Speedway, where the Nextel Cup series was racing Monday afternoon, lowered the flag in the victory lane to half-staff in his memory.