Some of our nation's hotspots for app development are fairly predictable - Seattle, San Francisco - but others will surprise you. North Carolina? New Jersey? Nashua, New Hampshire?
While the smaller markets on the list do have lower numbers of people employed in the field, their concentration in the overall job market is greater, giving them a higher "location quotient" - in other words, these are the areas most saturated with app developers.
Other areas of high concentration that didn't quite make the top ten? Portland, OR; Los Angeles, CA; Salt Lake City, UT; Minneapolis, MN; Madison, WI; St. Louis and Kansas City, MO; Dallas, TX; Cincinnati and Columbus, OH.