Ah! Mystery solved.
The Miss Teen International Pageant™ will be held on August 1st - 2nd at the North Shore Center in Chicago, Illinois.
I apparently was fortunate enough to see Jessica Brockman, Miss Teen Kentucky, whose publicity photo on the website looks refreshingly like an embarrassing junior-high photo (I think she even has braces). Looking at the other photos, the contestants appear to range in age from 15 to 42. Miss Teen Arkansas looks like she's trying out for the cover of Good Housekeeping.
The contestants seem to be from the usual range of 50 states and the District of Columbia, but apparently America's imperial ambitions have been moving at a faster clip than I remember: there's Miss Teen Canada, Miss Teen Nigeria, and most cryptically of all, Miss Teen Sunshine. Not to mention Miss Teen Your Name Here.