How Bourbon Got It's Name
Here's the answer, from StraightBourbon.com:
One of the first important Ohio River ports in Kentucky was at Maysville, which was then called Limestone. This port was already in use by 1784 when the Virginia legislature assigned "two naval officers or collectors" to the Falls of Ohio (now Louisville) and the "mouth of Limestone" (now Maysville) to supervise river traffic and collect tolls.
Bourbon County, which included the port at Limestone, was established the next year. The new county encompassed a vast region. It included virtually all of modern Kentucky to the north, east and southeast of Lexington. Limestone was the preeminent port for the whole region. Only a few years later, in 1789, Limestone and the rest of northeastern Bourbon County became Mason County, Virginia. Maysville is still the county seat of Mason County, Kentucky, today. After Kentucky became a state in 1792, many more new counties were carved from the original area known as Bourbon County and Bourbon County itself shrunk to its current modest size. In fact, thirty-four modern Kentucky counties were once part of Bourbon.
Because of that common heritage, the entire region continued to be known popularly for several decades as "Old Bourbon." During this same period, whiskey became the region's most important export. Because most people living there still called the whole region 'Old Bourbon,' any whiskey shipped from Limestone was invariably advertised and identified on barrelheads as 'Old Bourbon Whiskey,' no matter where it was actually made. Everyone at the time understood this name as simply identifying where the whiskey originated generally, i.e., somewhere in the region known as 'Old Bourbon.' More specifically, it meant any whiskey shipped to market from the famous port of 'Old Bourbon' at Limestone.
Eventually, this habit of referring to the whole region as 'Old Bourbon' died out and people unfamiliar with the practice began to assume that the word 'old' in the phrase 'Old Bourbon Whiskey' must have referred to the age of the spirit. It never did. In fact, the routine aging of whiskey was still several decades in the future.
Maysville is still known for its bourbon thanks to the Pogue family who operated a distillery in the area until 1955 and recently reopened in Bardstown, Kentucky. For more about them, visit: Old Pogue Bourbon