Interest in drones continues to increase in the United States. According to the research firm Gartner, drone unit sales are expected to grow this year by almost 40 percent. With news coming from the White House about a pilot program to expand commercial drone flights, the market seems primed for even more growth.

To help regulate an exploding industry, the Federal Aviation Administration (FAA) set up an unmanned aircraft registration system in December 2015. The FAA required anyone with a drone weighing more than 0.55 pounds to register before flying it outdoors for recreation. This requirement stayed in place until May 2017, when a federal court in Washington D.C. struck it down. Still, the data presented here includes nearly 820,000 drone registrations filed through February 2017.

Other researchers have looked at this data before in various ways. We've added an important methodological tweak in our approach. Not only do we view the data on a per capita basis -- adjusting for the population of each county -- but we also smooth the data with the Getis-Ord local statistic. This removes some of the variance in the raw data and makes "hot spots" on the map more obvious.

So where are the drone hobbyists located? According to our analysis, primarily in the middle of the country. Northern Colorado, eastern Montana, and the Dakotas over-index in drone registrations relative to the rest of the country. The western corner of Nevada and the Floridian peninsula also see plenty of drone action. Much of the South, meanwhile, remains a no fly zone.