Do I need to take my invites to a USPS if not hand cancelling?

This might be the dumbest question but here we go.

We went pretty minimal with our wedding invitations (just two pearlescent pieces and a belly band), so each invite is about as thick/heavy as like a standard hallmark card you’d get in the mail. Because of this, I’m almost certain they don’t need to be hand cancelled (no wax seal/special touches like that, either).

So my stupid question is—do I need to take them to the post office to mail them? There are about 150. I’m not super close to a USPS office, but sticking them in the drop box down my block feels… wrong?

Anyone else have a similar situation? What’s the standard procedure here? 😅