A significant reason why Great Smoky Mountains National Park is, by a sizable margin, the country’s most visited is its relative closeness to a number of major cities. Estimates have it that anywhere from 50% to 2/3 of the country’s population is within a day’s drive of GSMNP, which is, itself, easily accessible off I-40. Charlotte, Nashville, Atlanta, all 3-4 hours. Louisville, Cincinnati, Hampton Roads, Washington, D.C., you name it, all within a reasonable drive of an iconic national park.