The Midwest-based Culver’s Restaurant chain known for its Butterburgers and fresh frozen custard opened its 470th restaurant in Greenville, S.C., its first venture to the East Coast and the 20th state of operation. A second restaurant is planned for Fort Mills, South Carolina, in 2013. Culver’s, which was founded in Sauk City, Wisconsin in 1984, is on track to open four more restaurants before the end of the year, bringing the total number of 2012 openings to 29.