I thought the wave had crested. I was wrong.

Back in 2007, I first reported on an unprecedented convergence in American baby names: one letter was dominating the boys’ side. Across the style spectrum, everybody wanted their boys’ names to end in N. Almost a third of American boys were receiving -N names, making that ending more dominant for boys than the traditional -A ending was for girls. Nothing like it had ever been seen before.

2007 was the middle of the “Age of Aidans,” when dozens of rhyming names like Aidan, Jaden, Braedyn and Hayden stocked the boys’ top 1,000. That craze peaked around 2010, and the national -N rate showed signs of gradual decline. In 2017 the slide accelerated, seemingly forecasting an end to this trend of all trends. Not so fast. In 2018, the -N’s surged back.

The remarkable part of this story is that by every other measure, American baby names are becoming steadily more diverse. The percentage of babies receiving a top-1,000 name is at an all time low. The dominant names of English tradition, starting with John and Mary, are becoming rarities. Different regions of the country are diverging in name tastes. Parents feel greater freedom in name choices, and are embracing it in ever more dramatic fashion.

Even the -N names themselves are diverse lot. Rising names that helped fuel last years -N jump include word names like Ocean and Seven, imports like Bjorn and Ishaan, coinages like Zavian and Kaycen, revivals like Leon and Warren, surnames like Pierson and Callahan, and statement names like Zen and Zeppelin. All they have in common is that final letter.

It’s one of the only ways that style is more united today than in the past. We might not agree on much today. but we know what a boy’s name sounds like. From Aaden to Zyon, it ends in N.