The U.S. unemployment rate has gotten so low, that most Americans were not alive the last time it was at this level.

On Friday, the Department of Labor reported that the unemployment rate dipped to 3.6% in April, which was the lowest level since December 1969.

That means anybody younger than 49 years and four months hasn't been alive long enough to see the unemployment rate this low.

According to the U.S. Census Bureau, as of 2017, the median age of all Americans was 38.1, meaning that half of the population was younger than that age.

A further breakdown of ages shows that 64% of Americans were aged 49 or under. While some of them would have been born before December 1969, primarily the age group would have been born after.

The robust economy is likely the biggest factor working in President Trump's favor in his reelection bid, even as other factors, such as his low approval rating, cut against him. If the numbers remain strong in 2020, it will become more challenging for Democrats to campaign against the him on economic issues. The arguments are going to have to be more structural, such as arguing that the boom has been unequally felt due to deeper flaws in the American economic model.