Costco Wholesale Corporation (NASDAQ: COST) is the largest membership warehouse club chain in the United States. As of July 2011^[update] it was the sixth largest retailer in the United States, and the seventh largest retailer in the world. As of October 2007^[update], Costco is the largest retailer of wine in the world.

Costco is headquartered in Issaquah, Washington, United States and was founded in Kirkland, Washington^{[citation needed]} with its first warehouse in nearby Seattle. Costco has locations in the United Kingdom, Canada, Australia, Mexico, Taiwan, South Korea, Japan, and the United States.

Founded by James (Jim) Sinegal and Jeffrey H. Brotman, Costco opened its first warehouse in Seattle, Washington, on September 15, 1983. Sinegal had started in wholesale distribution by working for Sol Price at both FedMart and Price Club. Brotman, an attorney from an old Seattle retailing family, had also been involved in retail distribution from an early age.^{[citation needed]}

Wal-Mart founder Sam Walton had plans to merge Sam's Club with Price Club. In 1993, however, Costco merged with Price Club (called Club Price in the Canadian province of Quebec). Costco's business model and size were similar to those of Price Club, which was founded by Sol and Robert Price in 1976 in San Diego, California. Thus, the combined company, PriceCostco, was effectively double the size of each of its parents. Just after the merger, PriceCostco had 206 locations generating $16 billion in annual sales. PriceCostco was initially led by executives from both companies, but then Sol and his son Robert Price founded Price Enterprises and left Costco in December 1994.