A relatively small number of people in the US have the Varnum surname . The US phone listings for Varnums include about 1000 households. There are only about 400 Varnum surnames in the current on-line Social Security database. The Social Security database represents those people who both had a social security number and died between 1937 and 1995. The earliest birthdate of those Social Security listings is in the 1870's. These listings do not include women who married and died with another surname, nor does it include people who died without social security numbers or who were still living as of 1995.
Years ago, someone told my grandmother that the Varnums were actually all one family, but that does not seem likely. What is likely is that there are a few main branches of the family. I was surprised to find that there are also few references to Scandinavia and Germany, prior to the England, Ireland and Scotland origins. I have not traced back beyond the US colonial times yet.
I have found two Varnum "root" families that are heavily documented. These families are those of George W. and Hannah Varnum in Massachusetts during the 1600's and Enoch and Mary Mechling Varnum in Pennsylvania during the 1700s.
I have also partially compiled census, birth, marriage and death records from the 1600s-1800s that are available on the Internet. I have also included information from Massachusetts's records that I looked up about 10 years ago and the information that my immediate family has given me. I have begun correspondence with Varnum families from all over the US.
Current populations are concentrated in Maine, Massachusetts, New York, Pennsylvania, North Carolina, Georgia, Florida, Illinois, Michigan, Alabama, Oklahoma, Iowa, Missouri and California.