First, a few helpful links. Here are two useful pages from the FamilySearch.org Research Wiki:
I would also suggest searching the Research Wiki for "find ____ birth records." You just insert the name of the state for a Research Wiki article about finding birth records in any of the 50 states.
If birth certificates are not available, where do you go next? Well, the answer to that question involves listing almost every type of record available. Generally, the next place to look for birth information is in any record that might have recorded the birth. The alternatives are listed in the United States Record Selection Table in the Research Wiki. For birth information, the following types of records are suggested, including some I added:
- Vital records
- Church records
- Bible records
- Cemetery records
- Obituary records
- Newspaper records
- Census records
- Naturalization and Citizenship records
- School records
In many cases, the birth date can only be calculated from an age or assumed age in another record. There are a lot of reasons why you may not find a birth record. Here is a list of some of those reasons:
- The birth took place in an unexpected location. Sometimes babies don't wait around for the mother to be in a convenient place to be born. The mother could have been traveling or visiting relatives and the birth place my be difficult to locate. In some cases, the birth could have been outside of the country or at sea.
- The jurisdictional boundaries of the birth place may have changed. It is important to research the history of the boundary changes because changes in the jurisdiction of the location can affect where the historical records are located.
- It is entirely possible that no record of the birth was ever made. In this case, a calculated birth date is all that is available.
- There could have been a record of the birth, but the index of the record is incorrect or incomplete. The best practice, in the event a record cannot be located with an index, is to search the entire record both for a time period before and after the assumed date.
- You may be searching for the wrong family. The surname may be wrongly recorded or you have assumed information that is not accurate.
- The child could have been adopted, a foundling or illegitimate. Any one or more of these circumstances may prevent discovery of the correct birth record.
- The person may have changed their name later in life and never disclosed their birth name.
Most of the reference books about genealogical research have a chapter or more about vital records. Understanding the process of creating birth records will give you a much better chance of finding an appropriate record.