I was born and currently live in México but I just recently received my US citizenship. I want to fly from Brownsville, Tx to Houston, Tx, so it is a domestic fly. Can I board with my citizenship certificate? I always enter the US by car using my citizenship certificate and never have a problem about it. PS. My trip is in December 11th, so I can't receive my US passport in time for the trip.
What is needed is an acceptable photo ID, e.g., a Mexico passport if you also have one of those. Your citizenship is not relevant on a domestic flight. From the official list, there are also other IDs you may already have.
Your citizenship status does not matter for domestic flights. All you need is a form of identification document that is accepted by the TSA.
If you have one of those in hand, you can fly.