They aren't free, but if you need an internet connection and have a good cellular signal, a paid hotspot is another way to get Wi-Fi on the go. For example, maybe you're traveling to a rural area ...
One of the three major cell phone carriers in the US, AT&T Wireless owns and looks after its own cell ... while Unlimited Premium is $45 (which gives you 10GB of international data and 50GB of hotspot ...