I knocked down part of a wall and as a result need to move some outlet wires. I found a good and legal place to put a junction box but the existing wires are stamped 16amp (35yr old house),(I assume that means about a 14ga) and I have 20ga (romex 12/2)---the circuit has a 20amp breaker.
Can I join these two gauges with no problem or do I need to go get some lighter gauge wire?

Thanks for the help.

You can not have 16 amp wire on a 20 amp breaker. You could however drop the breaker down to a new 15 amp breaker. What is on this circuit that would require 20 amps? Most residential baseboard outlets are 15 amp.

Well, looks like I've got some work then-----I took all the info off the wire itself, checked and rechecked. Guess I got a problem.
FYI--the circuit includes all the outlets on the bottom floor (townhouse).
I'm going to have someone come over and check the wiring---thanks for the heads-up.

I'd actually check the wire diameter and consult the tables to be sure. 16 AMP may have been used long ago, but let's hope it wasn't 16 AWG.