pre paid cellphones

[Me]

preface: i know nothing about cell phones.  i have never used one before.
please dont laugh at me.

i need a throw-away pre-paid cell phone to use tommorow.  just tommorow, so im
not looking to waste $ on anything besides a pre-paid phone.

i am in canada, will use it here, and want to buy it here.  e.g. one of those
$100 fido or bell solo phones.

i will also need to use it in the united states.

can anyone tell me if these phones are capable of working in the united
states?

thanks. :P