This is the second-longest U.S. expansion in history. The obvious question on every investor’s mind: Is U.S. economic growth finally peaking?

Yet another economic data point suggests just that. Unemployment dipped below 4% for the first time in nearly 20 years. Why’s that matter? Hedgeye Demography analyst Neil Howe explains in the above video clip that the employment to population ratio is 97% of what it was in 2007 – the year of the last cycle peak. That means there’s very little – if any – room left to grow.

“The very best we can hope for is employment to population ratios where we were back in 2007,” Howe says in the clip above.

And while the data suggests there is still room to grow in employment to population ratios for 16 to 24-year-olds and 45 to 54-year old women, certain factors may prevent that: the former group is struggling to find work in, for instance, a peaking retail industry and the latter group has largely been staying out of the workforce to raise their children.

Watch the clip above for more.

Howe: Unemployment At 20-Year Low. What's Next? - early look