I think the prepaid SIM below would be handy to travel both USA and Canada.
Prepaid Sim Card for North America with Unlimited 4G / LTE Mobile Data + Unlimited Calls and Texts Within US, Canada and Mexico from The Largest USA Network AT&T
10days: CA$39.99, 15days: CA$54.99, 21days: CA$57.50, 30days: CA$74.99
I am an Australian tourist - will be in Canada and probably across border to Washington for 4/5 days. How/where can I get a sim card and how much will it cost me (data rates, etc).