Katrina Gilbert is one of them.
The 30-year-old single mom is at the center of "Paycheck to Paycheck: The Life and Times of Katrina Gilbert," a new HBO documentary executive produced by Maria Shriver that attempts to put a human face on the startling stat.
Filmed over the course of one year in Chattanooga, TN, the doc chronicles the highs and lows in the life of Gilbert, a mom of three who's barely scraping by on the $9.49 an hour she receives as a certified nursing assistant.
"I didn't expect to be a single mom of three children but I am and I'm trying to deal with it the best way I can," Gilbert says in the trailer above.
"Paycheck to Paycheck" debuts on HBO Monday, March 17 and will be available free online on HBO.com, ShriverReport.org and YouTube March 17-24.