When the latest Social Security Administration numbers for the top 1000 baby names came out a couple of weeks ago, dt reader Matt suggested looking at state-by-state lists of popular names, too. As he pointed out, Ava may have bumped Sophia out of the top ten in aggregate, but Sophia was #1 in DC.
That got me poking around low-population states like North Dakota, where it turns out it only took 8 Halles or 13 Jesses to make the top 100. The cutoff for California, meanwhile, was much higher (463 Gabriellas and 615 Ericks with a 'k' to get the #100 spot.)
And names that showed up in the top 25 for California--names like Jesus, Angel, and Luis, for example, don't even break the top 100 in ND. So not only is there a regional diversity in the popularity of names--something that's obvious when you pick traditionally Hispanic names--there's a difference in the number of kids given the most popular names.
Gelf Magazine actually compared the numbers, and found that the top 100 names accounts for fewer kids born in the US than ever--48% for boys, but only 32% for girls. That's a drop of almost 50% since 1945.