Not all supermarkets are created equal. For many Americans, stopping by a chain supermarket has become a major chore, involving long lines, rude employees, unsanitary conditions and poor selection. Consumer Reports recently conducted a survey of more than 24,000 shoppers to rank the best and worst out of 52 grocery store chains – and the results show how customer experience falls short at some megastores.

PHOTO GALLERY: Click Here to See the 12 Worst Supermarkets

Back in 1930, King Kullen Grocery Company in New York’s Long Island became the first supermarket (though some have disputed the claim) that offered a one-stop-shopping experience for groceries. Today, Walmart is currently the largest grocer, accounting for 22 percent of American food sales in 2010, followed by Kroger, Costco and Safeway. The portion of the market taken up by the four largest grocers in the U.S. continues to increase – accounting for 37 percent of food sales in 2010, up from 4 percent in 1912.

The consolidation has given consumers fewer shopping options – more than half of those surveyed by Consumer Reports had at least one complaint about their current store, while nearly a third cited two or more issues. The biggest complaint was a lack of open checkouts, followed by crowded or dirty aisles.

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Click here to see the 12 worst supermarkets according to the survey. All ratings are based on 24,203 responses, and the four categories – service (includes employee courtesy and checkout speed), perishables (food quality), price and cleanliness – were scored from “very satisfied,” “fairly satisfied,” “neutral, “fairly unsatisfied” and “very unsatisfied.” All scores are out of 100. The highest-rated supermarket, Wegmans, received a score of 88. The following are ranked from bad to worst.