Of all the automakers, Delaware's ties ran deepest with GM.

Without Delaware's du Pont family and the DuPont chemical company, GM might have disappeared along with Packard and Pierce-Arrow and dozens of other automakers of the last century.

"It certainly wouldn't have survived in the way that we conceive of General Motors today," said Kenneth Durr of History Associates in Rockville, Md.

Under founder William C. Durant, GM was facing collapse in 1920 when Pierre S. du Pont, a founder of the modern DuPont Co., stepped in. He seized control and put GM on course to become the world's largest carmaker.

"Durant put together this big shaky thing, and it took the kind of expertise that du Pont had...to really integrate it into a well-running machine," Durr said.

Besides sending DuPont Co. executives to GM, du Pont brought in Alfred P. Sloan, a fellow Massachusetts Institute of Technology grad, who became GM's legendary CEO for more than two decades. They introduced the modified military "line and staff" structure that became a U.S. corporate model.

The rescue was a case of self-interest. Pierre du Pont invested in GM as early as 1914 and became a director in 1915. After WW I, the DuPont Co. financial wizard John J. Raskob persuaded the company to invest in GM, seeing a good fit with DuPont's varnish, paint and artificial leather businesses.

It was. In the early 1920s, for example, DuPont researchers and GM solved one of the auto industry's biggest production obstacles, drying time for oil-based paints. They found, says Durr, that paints made with nitrocellulose — smokeless powder DuPont made for the war and wanted a civilian market for — dried quickly and could be sprayed over large surfaces. GM began using "Duco" lacquer in 1924, cutting drying time from two weeks to hours.

In that decade, DuPont and GM also developed such things as new refrigerants for GM's Frigidaire appliances and gasoline antiknock additives.

By the 1930s, a Chevy coupe would be coated with DuPont Duco lacquer, have a top of Fabrikoid artificial leather and have safety glass made with Pyralin, according to Hagley Museum and Library.

Local businessmen tried to get a GM plant for Delaware as early as 1931, but not until 1945 did GM reveal plans for its first new plant on the East Coast. The announcement did not mention that DuPont owned nearly a quarter of GM. It hailed it as part of a post-war decentralizing.

In 1949, however, the U.S. government brought an antitrust action charging du Pont family members, DuPont Co. and GM with conspiracy to restrain trade and monopolize certain products. DuPont was forced to divest its shares by 1965.

GM's close relationship with DuPont was never entirely severed, though. It remains an important customer and DuPont CEO Ellen Kullman was a director from 2004 until last December.