The Population Reference Bureau's Household Change in the United States does an excellent job summarizing the changing composition of America's 117 million households.
As the chart below shows, family households have steadily declined while one person households have steadily increased.
Also important to note is only 1 in 5 U.S. households are currently of the Ozzie and Harriet variety - a married couple with children.
This means the kids were well behaved, the Dad full of wise advice, the Mom elegantly dressed no matter the time of day or task at hand, and everyone was home every night for dinner.
We posted in the past on the shifting American family and this data provides more information on these changes.