The Federation of State Boards of Physical Therapy (FSBPT) is in the nascent stage of developing a Physical Therapy license compact. FSBPT's aim is to reduce regulatory burdens by allowing cross-state practice for licensed Physical Therapists. The nursing profession has had a nursing compact since 2000. According to FSPBT, 24 states participate in the nursing compact.
FSBPT's Advisory Task Force has recommended a similar model to the nursing compact.
The licensee participant must hold one valid, current, unrestricted license his or her primary state of residence, notify any remote states in which s/he will be practicing and pay a fee to the remote state.
The final language is expected to be ready for review in mid-2015. If a state wishes to participate in the PT license compact, that state will need to pass the final language into law. This likely requires state legislative action.
FSPBT has a series of articles and FAQs on their webpage.