In post since August 1994, Marybeth's tenure is the second-longest in US history. Only Thorvald Solberg -- remember him? -- served longer. He reigned from 1897-1930, a period of 33 years, but that was in the days before the internet and computers.
If you want to apply for the job, apply here -- but if you really want to run the show, apply here.
Many thanks to C.E. Petit, distinguished author of the Scrivener's Error weblog, for letting us know.