Historical Sketches of Kentucky by Lewis Collins was published in 1847. It includes a short report on each county of Kentucky -- the towns, the topography, the industries, the history.
In his sketch of Christian County, Collins wrote that Hopkinsville's population was 2000. Hopkinsville seems to have been the largest town of western Kentucky at that time. I suppose it was because of the excellent tobacco grown here.
Here are populations of some other county seats in the region, as cited by Collins.
Bowling Green: 1700
Paducah was the only rival in population to Hopkinsville that I found. Collins wrote that Paducah's population was "...in 1845, 1500 -- in 1847, presumed to be nearly 2000." I wonder what made Paducah's population increase by 25% in just two years.
And I wonder what percentage (if any) of the slaves who lived in these towns were included in these numbers. I think it's unlikely that Collins' population figures are accurate, but they are interesting.
Above: A portion of the U.S. map that accompanied Doggett's Rail Road Guide of 1847. "The working lines of railroad are shown in color." I don't see anything but towns and rivers in these parts.
Update: This is quoted from the Wikipedia entry for Paducah (italics added).
Paducah was incorporated as a town in 1830, and because of the dynamics of the waterways, it offered valuable port facilities for the steam boats that traversed the river system. A factory for making red bricks, and a Foundry for making rail and locomotive components became the nucleus of a thriving River and Rail industrial economy.
After a period of nearly exponential growth, Paducah was chartered as a city in 1856. It became the site of dry dock facilities for steamboats and towboats and thus headquarters for many bargeline companies.