You could either unlock your phone and get a US sim card or if you contact Koodo you can ask for the $45/month US recurring add-on which I believe is unlimited talk and text. (You'd have to ask what it includes or someone here can chime in)
Whenever we go to the states we use: https://roammobility.com/snowbird-plans . Check out the different plans. Just order a sim (they are also available at alot of gas stations and convenience stores in Canada) and activate it. They step you through configuring your phone. You'll have a working phone once you step off the plane. Of course your phone will need to be unlocked, which is free to unlock now.