I don't know American ways for Births Deaths & marriages, but if you can state the name & birth & death dates of relatives who have passed & where they were living & ask their offspring to contact you by email, that could work.Many boards don't like to post names of living persons.
Try putting one at a time these names in the Surname search, you may find your families that way.
The 1940 census may have members who are still alive also U.S. World War II Army Enlistment Records, 1938-1946.
Also Obituary columns in newspapers for family members.
Have a scroll through Ancestry's catalogue to find more,& search by county.
New collections for United States may help too.http://www.ancestry.com.au/cs/reccol/default
click on the little arrow in the white box to find the country you need.