Catlettsburg is a city in Boyd County, Kentucky, United States. It is the county seat of Boyd County. The city population was 1,960 at the 2000 census. However, the city's postal zip code serves a greater population of 10,029. Catlettsburg is a part of the Huntington-Ashland, WV-KY-OH, Metropolitan Statistical Area (MSA). As of the 2000 census, the MSA had a population of 288,649. Since the early 1990s, the commercial sector has grown due to its proximity to Interstate 64 and its location along U.S. Route 23 and 60, both major regional arteries which overlap in Catlettsburg and travel into the city of Ashland. Many commercial developments have developed on the southern end of the city along these routes.