I traveled all the way through the USA from the east coast to the west coast, by car and RV. I thought about getting a UMTS / LTE stick for my Notebook, too. But there really wasn't any need for this.
You can get FREE WIFI almost everywhere:
- Coffee Shops (Starbucks, etc.)
- Fast food Restaurants (Pizza Hut, McDonalds, KFC, etc.)
- Camp grounds
- Hotels
- Shops / Malls
- Libraries
SometimesIn rare cases you get WIFI access even here:
- Cinemas
- Grocery Stores
- Gas Stations
I can also tell you, that the UMTS internet coverage isn't that good when you plan to visit national parks or other nature reserves.
Whilst driving through the less populated middle of the USA there are times when you even don't get your cell phone working --> NO Service!
So if you really feel the need for uninterupted internet access, you should carefully check the coverage of your Mobile-ISP