The Gateway Arch in St. Louis looks like a smile turned upside down. But the city’s residents?
They’re the happiest folks around. We gleaned that from the results of a recent high-tech study of more than 100 million photos of smiling faces, snapped in 50 U.S. cities and posted on Instagram. Conducted by JETPAC CITY GUIDES and timed to the launch of the company’s latest travel app, the study relied on “geo-parsing” software that looked for patterns in the pixels and produced a “smile score” for each city — a value based on the average size of the smiles in the photographs.

St. Louis topped the charts, with a smile score of 54.7. Maybe there’s something in Missouri’s water, because Kansas City came in second, a mere 2.7 points behind. Rounding out the top 10 were Columbus, Ohio; Indian­apolis; Pittsburgh; San Antonio; Minneapolis; Jacksonville, Fla.; Detroit; and Raleigh, N.C. Want more? Go to JetPac.com to see the complete list and to find a link to the company’s new iPhone app, which curates images from Instagram to help users track down everything from top bars with women wearing lipstick to coffee shops full of moustached men.