Williamson County was created on February 28, 1839 (Laws, 1839, p. 110) and was formed from Franklin County. Present area, or parts of it, formerly included in: Franklin County (1818–1839) , Jackson County (1816–1818) , Gallatin County (1812–1818) , Johnson County (1812–1816) , Randolph County (1795–1816) and Knox, Northwest Territory (1790–1801) .
The County was named for Williamson County in Tennessee through the influence of emigrants from that county. The County Seat is Marion (1839-Present) . Some records lost or damaged in a fire on May 30, 1875

The Official County website is located at N/A . All departments below at located at the Williamson County Courthouse, 200 W. Jefferson, Marion, IL 62959 , unless a different address is listed below.
NOTE: The record dates below are from the earliest date to present time.
Williamson County Circuit Court Clerk has Probate Records from 1836 and Court Records from 1840 and is located at the address above. Phone Number: (618) 997-1301, ext. 114
Williamson County Recorder has Land Records from 1818 and is located at the courthouse. Phone Number: (618) 997-1301, ext. 101
Williamson County Clerk has Birth / Death Records from 1877 and Marriage Records from 1839 and is located at the courthouse. Phone Number: (618) 997-1301, ext. 101
County Treasurer’s responsibilities include the statutory duties required as County Treasurer and as Ex-Officio County Collector of Real Estate Property Taxes and Drainage District Taxes for the entire county.
Below is a list of online resources for Williamson County Court Records. Email us with websites containing Williamson County Court Records by clicking the link below:

Birth, marriage, and death records are connected with central life events. They are prime sources for genealogical information.
Illinois Department of Public Health, Division of Vital Records, 605 W. Jefferson St., Springfield, IL 62702-5097. It can take up to 6 weeks to get a vital record from Illinois.
A number of resources are available for individuals doing genealogical research using vital records filed in the state of Illinois. Births and deaths before January 1, 1916 and marriages before January 1, 1962 are recorded only in the office of the county clerk where the event occurred. Most county clerks have indexes to the records that are prior to 1916 that are available for the purpose of genealogical research. These indexes generally provide the name, date and place of occurrence and are located in county courthouses located throughout the state. Although self-service access to the indexes is generally permitted, the law limits physical access to the individual records to the clerk's staff. When you locate a record from the index, it will be necessary for the clerk to pull the record for you once you have paid the appropriate search fee. Please check with the county clerk for fees and policies on reviewing indexes.
Below is a list of online resources for Williamson County Vital Records. Email us with websites containing Williamson County Vital Records by clicking the link below:

Few, if any, records reveal as many details about individuals and families as do government census records. Substitute records can be used when the official census is unavailable
Countywide Records: Federal Population Schedules that exist for Williamson County, Illinois are 1840, 1850, 1860, 1870, 1880, 1900, 1910, 1910, 1920 and 1940.Other Federal Schedules to look at when researching your Family Tree in Williamson County, Illinois are Industry and Agriculture Schedules availible for the years 1850, 1860, 1870 and 1880.
The Mortality Schedules for the years 1850, 1860, 1870 and 1880.There are free downloadable and printable Census forms to help with your research. These include U.S. Census Extraction Forms and U.K. Census Extraction Forms.
Below is a list of online resources for Williamson County Census Records. Email us with websites containing Williamson County Census Records by clicking the link below:
Below is a list of online resources for Williamson County Maps. Email us with websites containing Williamson County Maps by clicking the link below:
Below is a list of online resources for Williamson County Military Records. Email us with websites containing Williamson County Military Records by clicking the link below:
There are many churches and cemeteries in Williamson County. Some transcriptions are online. A great site is the Williamson County Tombstone Transcription Project.
Below is a list of online resources for Williamson County Cemetery & Church Records. Email us with websites containing Williamson County Cemetery & Church Records by clicking the link below:
Below is a list of online resources for Williamson County Family Trees, web forums and other family type information. Email us with websites containing Williamson County Family Trees, web forums and other family type information by clicking the link below: