How many families are there in America?

The 2007 US Census says there were about 291M people in the US, with an average of 2.6 persons per household. That makes about 112 Million HOUSHOLDS in the US. Not quite families, maybe...

This document:
is from the 2000 Census. It says there are a total of 105.5 million households including 71.8 million family households, or 68.1% of total households. It goes on to break the family households into "married-couple", "female householder, no male present" and "male householder, no female present."

If the 2007 Census puts households at 112 million and the percentage of family households remains the same is it was in 2000, it's likely there are about 76.3 million family households in the US.