Some may have noticed that many families are missing in the St. Clair county census of 1870. Apparently, there were some problems relating to the aftermath of the Civil War,
and Union men being placed in positions of power, which created conflict in Ashville, Alabama, amongst other locations. Officials from all states were called to testify before the Senate in Washington, DC, regarding any problems encountered in their states. From testimony given, it appears the census taker was scared to take the 1870 census in the Ashville area. The book is titled Testimony taken by the Joint Select Committee to Inquire into the Condition of Affairs in the Late Insurrectionary States. Alabama. Volume II. Washington. Government Printing Office, 1872. The complete book is available for free on Google Books. An excerpt regarding the troubles in Ashville and titled Reconstructions Years History, can be found on StClairCountyAL.com which is an excellent source for historical information about St. Clair County, Alabama.
Try searching the "Joint Select Committee" book for your surnames or cities of interest. You may be surprised at what you find - I certainly was!