May 4, 2013 Subject:
If you want actual Union County Arkansas file...
Go to http://archive.org/details/7thcensus0008unit This link goes to Alabama description, but is really the file that should be here. I was looking for Lawrence County, Alabama but it only showed Union et. al counties for Arkansas. The files were mixed up.
August 10, 2012 Subject:
This census is for Alabama. I have not been able to locate the Union County, Arkansas 1850 Census in this collection.