Holding a professional engineering license doesn't automatically qualify you to work as an engineer in another state. However, once you've obtained your engineering license in one state, you're on the fast track to licensure after crossing state lines. A new state will either issue a new license for that state, or issue an endorsement to your current license that certifies you as a professional engineer for that state as well. Steps needed to gain new licensure include completing paperwork, paying required fees and waiting for everything to be processed.
All states require professional engineers to pass an exam, usually administered by the National Council of Examiners for Engineering and Surveying (NCEES). Once you pass this exam for your first license, most states do not require you to take the exam again. The new state where you are seeking a license will verify your exam results with the NCEES. The NCEES administers different types of tests. The tests you passed to obtain your first license must be equivalent to the test required for licensure in the new state to which you are applying.
In addition to proof of passing the required examination, the new state where you're seeking an engineering license may require other paperwork, including school transcripts, supplementary experience records and references. Some states also require a criminal background check. Each state has its own requirements for documentation. Your state's Board of Engineering can provide you with a list of all the paperwork you will need.
To obtain a new engineering license or an endorsement on your current license, you'll need to complete the application for a license in the new state. Because you already have an engineering license from one state, you may not have to fill out every section of the application. For example, Washington State doesn't require applicants who already hold licenses to complete the experience record portion of their licensing application. You must also pay a licensing fee, which will usually be the same whether you are requesting a first-time license or an addition to a license you already have.
If your previous professional engineering has expired prior to your license application in the new state, you may be treated as an unlicensed applicant and have to take the licensure exam again. This may be dependent on when your previous license expired. In Texas, you don't have to retake the exam if your former license expired within the previous two years.