New Years Day (January 1) - most businesses closed; hangovers from parties the previous night, football parties. Primarily a secular holiday, and the major celebration occurs the previous night.
Martin Luther King Day (third Monday in January) - many government offices and banks closed; diversity-awareness programs.
St. Valentine's Day (February 14) - no significant closures; romantic evenings out.
Presidents Day (third Monday in February) - (also Washington's Birthday) - many government offices and banks closed; few observances, many stores have sales.
St. Patrick's Day (March 17) - no significant closures; Irish-themed parades during the day, and parties in the evening. Travelers may want to be wary of the drunken revelry and associated drunk driving crackdowns.
Easter (a Sunday in March or April) - few significant closures; Christian religious observances.
Passover (timing somewhat similar to Easter; lasts a week) - Jewish religious observances.
Memorial Day (last Monday in May) - most non-retail/tourism businesses closed; some patriotic observances; extensive travel to beaches and parks; traditional beginning of summer tourism season.
Independence Day / Fourth of July (July 4) - most businesses closed; patriotic parades, fireworks after dark.
Labor Day (first Monday in September) - most businesses closed; extensive travel to beaches and parks; traditional ending of summer tourism season.
Rosh Hashanah and Yom Kippur - Jewish religious autumn holidays.
Columbus Day (second Monday in October) - many government offices and banks closed; few observances.
Halloween (October 31) - no significant closures - trick-or-treating and costume parties in the evening.
Veterans Day (November 11) - many government offices and banks closed; some patriotic observances.
Thanksgiving (fourth Thursday in November, unofficially the Friday and weekend after) most non-retail businesses closed; family gatherings, on Friday major Christmas shopping begins.
Christmas (December 25) - most businesses and restaurants closed the evening before and all day; exchanging gifts, Christian religious observances. If you need food from a restaurant, your best bet will be hotels and Chinese or Indian restaurants. People from non-Christian religions often go to the movies and eat at Chinese restaurants on Christmas.