The ‘labor force’ does not consist of all people between 16 and 65. Many of them are students, housewives, retired, etc.
The BLS definition of the labor force is those people who either have a job or business, or have taken action during the past 4 weeks to find a job or start a business. This is in some ways a judgment call, but there really is no better way anyone can think of to exclude people who for various reasons are not interested in earning money right now.
It is still very odd that the numbers have gone flat for the first extended (more than a year) time in 60 years.
Obama’s gang are playing with numbers. Jimmy Carter’s team of commie peanuts didn’t even get away with this, much less even try it.
That would certainly explain it. Big drop in 2009 with little recovery. I had thought that the labor force was the potential number of workers while the participation rate defined who was employed or seeking work. Given the numbers, your explanation sounds sensible.