Barring a recession, it appears the US is running out of people. We aren't. The chart is misleading.
The Wall Street Journal asks Is America Running Out of Unemployed People to Fill Jobs?
For every job opening in America, there's now barely more than one unemployed person available to take it. In mid-2015, there were 2.3 million more unemployed people than open jobs. By January, the gap had narrowed to 372,000.
Pool of Potential Workers
There is a huge pool of workers as shown by the following Advisor Perspectives chart on the Labor Force Participation Rate.
In every age group except 55 and over, fewer people are working on a percentage basis than in 2000.
Many of them are not counted as "unemployed" even though they want a job. Why?
Wanting a job is not enough to be counted. Nor is looking for a job on Monster or other places. Before the BLS counts you as unemployed, you actually have to apply for a job, send out a resume. or have an interview.
Admittedly, many of those who are not working are unskilled. However, fast food places and most retail trade jobs do not require skills other than to show up for work on time and be polite to customers.