In the first quarter of 2015, the millennial generation passed generation X (which had only recently passed the baby boomers) as the largest generation in the U.S. workforce.
You probably noticed rumblings of change in your association's ranks as long as a decade ago, so we've long known this was going to happen. As of the first quarter of 2015, the millennial generation (ages 18 to 35 in 2015) now makes up the largest portion of the U.S. workforce and, by extension, your association's market of members and prospects. Time marches on.
U.S. Workforce by Generation
Silent Generation (5 million):
Source: Pew Research Center
[This article was originally published in the Associations Now print edition, titled "Millennials, Officially the Most."]