adoptees have unrestricted access to their obc

as of January 1, 2008, adult adoptees have unrestricted access
to their original birth certificates in six states:

Alabama (birth parents can file contact preference form) AD AP  

Alaska (passive registry for birth parents) AD AP

Kansas (adoptee can access court/agency files in addition
to obc; active registry for birth parents) AD AP

Maine (starting 1/1/09; until then, only adoptees born prior to 1953 may access their obc) AD AP

New Hampshire (birth parents may  file contact preference form)  AD AP

Oregon (birth parents may file contact preference form) AD AP BP BS

in four states, adult adoptees born prior to  or after a particular year
(in parentheses) have unrestricted access to their original birth certificates:

Maryland (pre 1947) AD AP BP

Montana (pre 1967) AD AP

Ohio  (pre 1964) AD AP

Virginia (post 1994) AD AP

states which offer a mutual consent registry are listed in color

states which provide non-identifying information to adoptees
are marked with the abbreviation AD

states which provide non-identifying information to adoptive parents
are marked with the abbreviation AP

states which provide non-identifying information to birth parents
are marked with the abbreviation BP