Beginning in the 1920s, self-service supermarkets began to displace small neighborhood grocery stores in the United States, and during the next twenty years, tens of thousands of small stores went out of business. For major grocery shopping, supermarkets offered lower prices and a greater variety of products. Still, a shopper needing just a few common items, such as bread and milk, might not want to travel to the supermarket (which might be miles away) or deal with long lines at the checkout stands. Ironically, this created a niche for small, local markets offering the most frequently purchased groceries. They grew modestly until World War II and rapidly expanded after the war. Their main reason for success was their fast service—the customer was in and out of the store in minutes, having picked up a missing ingredient for that evening’s meal or the makings of the next morning’s breakfast.