Vital Records are one of the most accurate records for genealogy and ancestry research and are typically, Birth records, Marriage records and Death records. Most vital records are kept at the county level within the state the event took place.  The following links may help you in your search.

Vital Records by State
http://vitalrec.com/index.html

CDC Vital Records Directory
http://www.cdc.gov/nchs/w2w.htm