By the beginning of 2013, Walmart's activities had spread beyond its historical roots in domestic discount centers. The number of domestic discount centers had declined to 561 from a high 1,995 in 1996. Many discount centers had been converted to supercenters, which had in creased to 3,158 stores. Walmart Supercenters combined full-line supermarkets and discount centers into one store. Walmart also operated 620 Sam's Clubs, which were warehouse membership clubs. lri1999,'Walmart opened its first Neighborhood Markets, which were supermarkets, and it expanded to 286 in operation by 2013.