Final answer:
The Department of Health and Human Services and the Department of Homeland Security are the two lead federal departments aiding in the development of higher interoperability among states and emergency responders.
Step-by-step explanation:
The two federal departments that have taken the lead in assisting states and regional emergency responders develop a higher level of interoperability are the Department of Health and Human Services and the Department of Homeland Security.
After the September 11 attacks, the Department of Homeland Security was established to centralize disaster response and facilitate better communication and cooperation among agencies, as noted with the creation of FEMA within its structure. The shortcomings observed in FEMA's response to Hurricane Katrina highlighted the critical need for improved interoperability between different government agencies and emergency responders.