A complete guide to airline policy on emotional support animals

UPDATE: Feb. 28, 2020: The U.S. Department of Transportation proposed in January a set of rule changes for emotional support animals on passenger planes. Under the new guidelines, only service animals like guide dogs would be allowed to fly. Other support animals would be banned from the main cabin. It's not official yet, but if the rules change almost all support animals now allowed would only be allowed to travel in cargo areas. 
This story was originally published in 2018, but has been u