title: Merck & Co.
context: The company was established in 1891 as the United States subsidiary of the German company Merck, which was founded in 1668 by the Merck family. Merck & Co. was expropriated by the US government during World War I and subsequently established as an independent American company in 1917. While it operates as Merck & Co. in North America, the original Merck based in Darmstadt holds the rights to the Merck name everywhere else. Merck & Co. is the world's seventh largest pharmaceutical company by market capitalization and revenue. Its headquarters is located in Kenilworth, New Jersey.[4] The company ranked No. 78 in the 2018 Fortune 500 list of the largest United States corporations by total revenue.[5]
question: When was Merck founded?
answers: 1891