1641 - First European settlement named Vriesendale.

1686 - Town of Orange (Orangetown) organized.

1693 - First county census (called Orange County): 219 inhabitants.

1712 - The Concklin family established first known farm.

1719 - Precinct of Haverstraw organized.

1724 - Jane Colden, first American female botanist, was born.

1727 - Dual county seats set up in Tappan and Goshen.

1771 - Brickmaking business began in Haverstraw.

1776 - First fire departments established throughout county.

1790 - County population: 18,492.

1791 - Town of Clarkstown created.

1798 - Rockland County separated from Orange County.

1807 - Robert Fulton invented the first steamboat in Clermont.

1812 - The first local newspaper, The Palladian, went to print in Haverstraw.

1826 - U.S. government built the first Hudson River lighthouse at Stony Point.

1830 - Nyack to Suffern Turnpike completed.

1832 - The Erie Railroad began operation in the county.

1865 - Stony Point incorporated.

1888 - The Great Blizzard dumped 21 inches of snow.

1890 - County population: 35,162.

1896 - Suffern incorporated.

1897 - The Missionary Training Institute relocated to Nyack; later named Nyack College.

1900 - The Palisades Interstate Park Commission established

1902 - Spring Valley incorporated.

1906 - Haverstraw Landslide Disaster occurred.

1911 - Letchworth Village established.

1924 - Bear Mountain Bridge opened.

1929 - Christie Airport in New City began operation.

1933 - James Farley of Grassy Point appointed U.S. Postmaster General.

1936 - Creation of the New City Library

1937 - Maxwell Anderson's play, High Tor, opened.

1941 - The Tolstoy Foundation in Valley Cottage founded for Russian refugees.

1955 - Tappan Zee Bridge opened.

1965 - The sloop, Clearwater, set sail.

1998 - Rockland County celebrated its bicentennial anniversary

1999 - Estimated population: 284,022.