Political Wire offers this helpful list:
6:00 pm EST
Indiana (East), Kentucky (East)
7:00 pm EST
Florida (Peninsula), Kentucky (West), Indiana (West), Vermont, Georgia, New Hampshire, Virginia, South Carolina
7:30 pm EST
North Carolina, Ohio, West Virginia
8:00 pm EST
Alabama, Connecticut, Delaware, Florida (Panhandle), Illinois, Kansas, Massachusetts, Maine, Michigan, Missouri, Mississippi, Maryland, New Jersey, New Hampshire, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas
8:30 pm EST
Arkansas
9:00 pm EST
Arizona, Colorado, Lousiana, Minnesota, New Mexico, Nebraska, New York, Rhode Island, South Dakota, Texas, Wisconsin, Wyoming
10:00 pm EST
Idaho, Iowa, Montana, Nevada, North Dakota, Oregon, Utah
11:00 pm EST
California, Hawaii, Washington
12:00 am EST
Alaska