In <a href="https://en.wikipedia.org/wiki/Kentucky" id="mwAT8" rel="mw:WikiLink" title="Kentucky">Kentucky</a>'s <a href="https://en.wikipedia.org/wiki/Mammoth_Cave_National_Park" id="mwAUA" rel="mw:WikiLink" title="Mammoth Cave National Park">Mammoth Cave National Park</a>, a Cave Research Foundation exploration and mapping team discovers a link between the Mammoth and Flint Ridge cave systems, making it the longest known cave passageway in the world.