Reconstruction Period Research Forum
The Freedmen's Bureau, 1865-1872
This has been posted many times before, but probably deserves another look.
NARA site containing descriptive pamphlets for download:
3. Marriage Records (Headquarters)
The NARA site contains a link to each of the associated Descriptive Pamphlets (DPs) in .pdf format.
The link below is to the DP for Texas Field office records (for example). It describes the organization of the Field Offices, locations, and available records for each location.
The NARA link provides an overview to all available records/resources:
Messages In This Thread