Most airports do have wifi, and a lot of them in the states use a wifi service by the name of boingo.
www.boingo.com
I use it a lot when I travel. If I am doing a lot of travel in one day for work...it's great - the boingo daily service will transfer from one airport to the next, which is a huge plus!!!
You can also do a monthy plan, which if traveling a lot in a certain time frame - is definitely the way to go
😉