I'm not aware of any reciprocal licensure with engineering. It may exist, but to my knowledge you have to hold a PE in the state where the plans are to be used. ie. I have to hold a Cali license if I am stamping plans for a Cali project despite the fact I have a Colorado license.
I mis-understood the discussion for this. Re-evaluating my earlier post:
Once you get a primary license (lets say California), that license represents your examination (at least for other states). If you apply for comity (lets say New York), you have to fill out the entire application as if you are a new engineer, except that you provide your primary license information in place of the exam requirements. The new state (New York), has the option to accept or deny the exam substitution at thier descresion. This will then provide you a stand alone license that is not affected by your California license (except for criminal activity). If your Cali license expires, your NY license remains valid and vice-versa. (note: some states may differ from this, I am not aware of any that do).
Now lets say you want a 3rd license (New Jersey). When you apply for that license (again, filling out the entire application), you would then have to provide your Cali info first (because it's your primary license and represents your examination) and your NY info second (because you got it through comity). If your Cali license is no longer valid, you cannot substitute your NY license as your primary because you did not take an exam for NY. You would then have to re-instate your Cali license (which may include re-taking the exam) in order to complete the New Jersey comity application.
My key point is that it is critical that you keep your primary license current. If it lapses, you run the risk of not being able to obtain licensure in other states (or being able to re-instate your primary) without having to re-take the exam.