3rd Monday in February. Not all states. The original version of the holiday was in commemoration of George Washingtons birthday in 1796.
A regional holiday in Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, District of Columbia, Hawaii, Idaho, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wyoming.
Information provided by www.officeholidays.com