The York County Heritage Trust (YCHT) was founded in 1999 after a merger of the Historical Society of York County (HSYC) and the Agricultural and Industrial Museum of York County (AIM).       The history of HSYC began in 1895 when a group of concerned citizens met and decided to collect, preserve and interpret the history and culture of York County. The Society's original focus was the development of a library to serve as a repository for the County's genealogical resource material. By 1900 a growing collection of artifacts led to the opening of a museum. In 1958 the Society moved to its present location at 250 East Market Street. Today, this site houses the YCHT's museum and library.       In 1966 the HSYC acquired the Golden Plough Tavern (c.1741), the General Gates House (c.1751) and the Barnett Bobb Log House (1812). Two years later the Society acquired the Bonham House (c. 1885). These historic sites are furnished and interpreted to their times and provide a window to a century and a half of life in York.       The history of AIM also began with a group of concerned citizens desiring to collect, preserve and interpret York County's history. This group's focus was directed toward the agricultural and industrial heritage of the county. In 1991, after two years of preparation, a museum opened in the old Eastern Market House (c. 1886). In 1992 AIM acquired an industrial complex consisting of six buildings (c.1874 to 1955). Three of the buildings were renovated and now house the industrial portion of the collection. The Worker's House (c. 1875) was opened in 1995 giving visitors a glimpse into the life of a working class family around the turn of the century.       Today, the York County Heritage Trust maintains eight sites that preserve and present 300 years of York County's rich and diverse history.