In an ATIS broadcast, is the visibility in statute or nautical miles?
The FAA has this handy chart to decode METARs (which are the printed version of the ATIS) and TAFs.


  Prevailing visibility; in U.S., Statute Miles &amp; fractions; above 6
  miles in TAF Plus6SM. (Or, 4-digit minimum visibility in meters and as
  required, lowest value with direction)