Hamilton County is in Southern Illinois. It was formed in 1825 and is named for Alexander Hamilton, the first U.S. Secretary of the Treasury.
Birth and death records have been kept since 1878. Marriage records and Probate records date to the formation of the county and the earliest land records are from 1835. Only some probate records can be found on FamilySearch.org.
The County Clerk’s office holds the vital and land records. The courthouse is location at 100 S. Jackson St., McLeansboro, IL 62859. The form to order vital records is at https://www.hamiltoncountyillinois.com/wp-content/uploads/2016/06/genealogy-application-1.pdf.
The IRAD depository at Southern Illinois University holds some probate and naturalization records for this county. A useful site with several types of records is the Yesterdays of Hamilton County, Illinois site at http://www.carolyar.com/Illinois/HamiltonCounty.htm.
Note: This was originally published in the "County Spotlight" column in the Illinois State Genealogical Society Newsletter (July 2020).