Jefferson -- U.S. County in Oregon Population (2000): 19009 Housing Units (2000): 8319 Land area (2000): 1780.782935 sq. miles (4612.206431 sq. km) Water area (2000): 10.384820 sq. miles (26.896560 sq. km) Total area (2000): 1791.167755 sq. miles (4639.102991 sq. km) Located within: Oregon (OR), FIPS 41 Location: 44.579150 N, 121.235587 W Headwords: Jefferson Jefferson, OR Jefferson County Jefferson County, OR