a factor with levels Alabama
,
Alaska
, Arizona
, Arkansas
, California
,
Colorado
, Connecticut
, Delaware
, District of
Colunbia
, Florida
, Georgia
, Hawaii
, Idaho
,
Illinois
, Indiana
, Iowa
, Kansas
, Kentucky
,
Louisiana
, Maine
, Maryland
, Massachusetts
,
Michigan
, Minnesota
, Mississippi
, Missour
,
Montana
, Nebraska
, Nevada
, New Hampshire
, New
Jersey
, New Mexico
, New York
, North Carolina
, North
Dakota
, Ohio
, Oklahoma
, Oregon
, Pennsylvania
,
Rhode Island
, South Carolina
, South Dakota
,
Tennessee
, Texas
, Utah
, Vermont
, Virginia
,
Washington
, West Virginia
, Wisconsin
, and Wyoming