There are several men named Johnson whose name you can run unto looking at the history of Gallatin County.  

The first is a man who ran a mill on Eagle Creek at Sparta, about whom I know nothing more.

 The second is one Col. Robert Johnson (July 17, 1745 – October 15, 1815).  Johnson is a prominent figure among Early Kentuckians, and primarily lived at a place about 2 miles west of Georgetown, and a place he called Great Crossing, because it’s where there was a large ford over the Elkhorn there where buffalo crossed.  Johnson was a state representative for 8 terms, a state senator, a delegate to the first two Kentucky Constitutional Conventions, and a fighter of Indians.  He was most notably at the battle at Bryant Station. 

The Great Crossings congregation founded May 28th and 29th, 1785 in Johnson’s  house, with Elijah Craig, of the Traveling Church.

Col. Robert Johnson also saw the need for a road to the river, and was responsible for laying out the road Gallatin Countians know as Johnson Road.  It was built as part of a longer road going from The Ohio River to Georgetown.  My speculation is that from Warsaw, it took Johnson Road to Glencoe, up the hill on what is now Poplar Grove, to Owenton, and then Rt. 227 south.  That’s an educated guess.

While there were earlier settlers in what is now Warsaw (see the articles Nancy Gullion wrote)   link  Johnson was the man who laid out the town and called it Great Landing, a name to “bookend” his “Great Crossing” in Georgetown.  He was living in Warsaw when he died. and is buried at the Great Crossing.

His son is Col. Richard Mentor. Johnson (October 17, 1780 – November 19, 1850), and even more noted figure in US history, and Vice-President of the US under Martin Van Buren. One biographer notes that he “partook strongly of that high ones integrity and courage which marked the times in which he lived ;” another notes he had affairs with at least four other Congressman’s wives and at least two of his own slaves.

If you run into the name Cave Johnson, (Wikipedia) that’s Robert’s brother.