Retail environment shifts.(Stores, Stores, Stores)(Illustration)

There are well over 1.6 million retail stores in the U.S. today, according to RoperASW. Their distribution continues to shift from independent merchants to national chains.

Stores selling and servicing cars and automotive equipment account for more than 12% of U.S. merchants and 5% of private-sector jobs. There are still close to 100,000 gas stations, but that's half as many as existed in 1975. Many have grown larger and serve more customers; others have found it more profitable to remove their service bays and turn them into convenience stores, which once were a sideline.

Used car dealers--typically much smaller than those selling new cars--continue to outnumber new car dealers by more than 70%. Used car sales (an estimated 43 million vehicles in 2003) are typically two-and-a-half times those of new car sales. With the average vehicle more than eight years old, there's plenty of business for stores selling tires, auto parts and accessories. Although their …