Here are some helpful links to information about Jefferson County:

DeSoto Historical Society	Herculaneum Historical Society	Arnold Historical Society
Jefferson County Historical Society
Festus/Tanglefoot Historic Association	2009 Jefferson Co. MO Data Book	Kimmswick Historical Society Museum
Jefferson County Genealogical Society
Historical Townships MORE Township Info from John W. Pierce	History of Jefferson County and the LEE Family by C.O. LEE	Post Offices From 1876 and 1898
Jefferson College History Center, Hillsboro
Index to the 1830 Census for Jefferson County, Missouri	A Directory of Towns, Villages, and Hamlets Past and Present of Jefferson County, Missouri	Jefferson County MO Message Board (Ancestry)
Missouri History Museum
Jefferson County's  portion of Goodspeed's 1888 History of Franklin, Jefferson, Washington, Crawford, and Gasconade Counties, Missouri	Surname List and Researchers	Marriage Records of Jefferson County (Brian Oster's site) sorry, this site is no longer available
Missouri State Archives - Jefferson City, MO (Searchable Sections) French and Spanish Land Grants Land Patents: 1831 - 1969 Missouri Birth & Death Records, Pre-1910 Missouri Death Certificates 1910 - 1959 Missouri Supreme Court Historical Database Soldiers' Records: War of 1812 - World War I Missouri's Judicial Records (Probate & Circuit Court) Coroner's Inquest Database Naturalization Records, 1816 - 1955

National Archives and Records Administration	Gov't Land Office Bureau of Land Mgm't	FREE! 1940 U.S. Census
State Historical Society-Columbia, MO	St. Louis City Public Library Resources, Obits, etc...	Missouri State Genealogical Society

More Missouri Links:

The Official LDS Search Website	Cyndi's List of Genealogy Sites on the Internet
RootsWeb Missouri Resources	Missouri Birth, Death, and Marriage Certificates - How to order
Missouri State Library	Nettie Mae's Online Missouri Death Index
"Gone But Not Forgotten" Missouri Pioneers	Dave Lossos' Genealogy in St. Louis
St. Louis County Library

Other Links:

"RootsWeb's WorldConnect Project: Connecting the World One GEDCOM at a Time" has over 14 million names on file and growing steadily. This resource has a great search feature to enable searches by name, birth place and death place. You can search and contribute GEDCOMs FREE. You can also remove them at any time.