Area code 859 was created in a split from area code 606 in 1999.
When an area code is split, normal practice calls for the largest city to retain the old area code in order to minimize disruption to existing businesses and the community. Thus, conventional wisdom would have suggested that Lexington and Northern Kentucky should have retained 606 in the 1999 split. Lexington was by far the largest city in the old 606 territory. Combined, Lexington and Northern Kentucky accounted for two-thirds of the old 606's population, along with the great majority of its landlines and cell phones. However, several counties in eastern Kentucky are among the poorest in the nation. The Kentucky Public Service Commission and BellSouth (now part of AT&T), then the region's main telephone carrier, decided to let the rural portion retain 606 to spare this notoriously impoverished area the added expense and burden of switching to a new area code.
Under current projections, 859 is expected to remain in its current configuration until about 2047.[1] This is despite the fact that the Cincinnati local toll area extends into both Northern Kentucky and southern Indiana, meaning that several numbers in Cincinnati's 513 and the Indiana suburbs' 812/930 are not available for use.
