But there's another, useful variable to consider: Age.
The households of middle-aged people earn about $20,000 more each year, on average, than households of people in their late 20s and early 30s. And they earn roughly $30,000 more than people age 65 and over (note that this difference includes income from Social Security and retirement).
None of this is terribly surprising — income over the life cycle is a curve, and it peaks when people are in their late 40s and early 50s.
Still, it's useful to recall that when we talk about average household income for the nation as a whole, we're lumping in lots of disparate households. A 24-year-old who makes $27,000 a year is in a much different position than a 45-year-old making the same amount.
A few notes on the data:
* All numbers represent pre-tax income.
* Income earned through work includes both money people earned on their full-time job and freelance income.
* Government assistance and benefits includes unemployment compensation, food stamps and veterans' benefits, among other things.
* "Other" includes financial support from others as well as rental and property income.
* The data come the Bureau of Labor Statistics. Here's the spreadsheet.