National Stock Car Association... or something like that. Founded on the East coast of the US in 1947 by Bill France. Featured great drivers like Junior Johnson and Lee Petty in the '50s. Car's were almost completely (85-90%) stock, which in a bad thing when it comes to safety. Most tracks were very twisty, and on unpaved roads. Most early NASCAR stockers topped-out at around 110mph, give or take a few. Of course, 4-wheel drum brakes were standard fare, and they hadn't even though of roll bars or window netting until the early '60s. In a accident, drivers could be killed easily. Since cars back then were very primitive, driver's had to work alot harder and drive alot better than they do today, with the safety and the aerodynamics and the super hi-tech V8's. Chrylser and Oldsmobile were very involved with NASCAR in throughout the '50s. By the latter-half of the '60s, Ford/Mercury and Dodge/Plymouth were the only teams really involved with racing. Engineers had essentially just discovered aerodynamics, and cars such as the Ford Torino Talladega and Dodge Daytona incorporated the latest in hi-tech aerodynamic aids. Suspensions and drivetrains had also gotten considerably better, but not to the point were it took the 'fun" out of driving. Safety had improved vastly, too, in part because of a crash in which Richard Petty ended up with hundred of shards of glass in his eyes. Materials were made better and stronger, and multi-point roll-barrs were used. Materials were also made out off more-modern weight-saving meterials, in an effort to make the cars that much faster. Hemi cylinder heads were used on Ford and Mopar engines by around '64. Converting a normal wedge-headed engine to a hemi one added about 85hp. By the '70s, it became more of a business thing than really racing, with more and more money involved and cars getting less and less 'stock."
'60s Nascar stock cars
Mopar Charger 500/Daytona, Road Runner Superbird
Ford Torino Talladega, Mercury Cyclone Spoiler