Muhlenberg County, Kentucky was formed in 1798 from Logan and Christian counties, Kentucky. Christian County, Kentucky was formed in 1796 from Logan County, Kentucky. Logan County, Kentucky in turn was formed in 1792 from Lincoln County, which was formed in 1780 from Kentucky County, Virginia.
How does this info help me? If your ancestor lived in what is today Muhlenberg County, Kentucky in 1790, you would need to check records stored at the Lincoln County, Kentucky courthouse. It can be confusing to know which county to search for ancestral records, as county boundaries have changed so often over time. The website Genealogy Inc hosts FREE rotating county boundary maps for most U.S. states that can help you with this challenge. Here are the links:
You can adjust these cool maps, “made with the use of AniMap Plus 3.0 & with the Permission of the Goldburg Company” just to the right year you wish to examine. Here is a map of Kentucky the year it split away from Virginia (1792):
You can follow the link to Kentucky to see what boundary lines looked like other years during the state’s history.