Regions of the Nuclear Regulatory Commission
|Region I||King of Prussia, Pennsylvania||north-east||26||17|
|Region II||Atlanta, Georgia||south-east||33||18|
|Region III||Lisle, Illinois||northern mid-west||24||16|
|Region IV||Arlington, Texas||southern midwest and west||21||14|
These four regions oversee the operation of 104 power-producing reactors, and 36 non-power-producing reactors. This oversight is done on several levels, for example:
- Each power-producing reactor site has Resident Inspectors, who monitor day to day operations
- Numerous special inspection teams, with many different specialties, routinely conduct inspections at each site
- Whistleblower reports are investigated by the Office of Enforcement, specifically the Allegations branch 
The NRC previously had five regions. Region V was headquartered in Walnut Creek, California and was responsible for activities in the seven far-west states: Alaska, Arizona, California, Hawaii, Nevada, Oregon and Washington. The NRC decided in September 1993 to consolidate Regions IV and V into a single Region headquartered in Arlington, Texas. On April 4, 1994, NRC Region V was abolished, and the NRC Region IV office in Arlington, Texas was given expanded responsibilities to include the seven states formerly governed by Region V. The former NRC Region V office in Walnut Creek remained open as the redesignated Walnut Creek Field Office, supporting resident inspection activities at power plants in the Pacific states of Washington, Oregon and California until October 1, 1998, when the Walnut Creek Field Office was abolished to further reduce costs.
- "NRC to restructure regional functions in west; Walnut Creek to be Field Office" (PDF) (Press release). Washington D.C.: Nuclear Regulatory Commission. September 22, 1993. Retrieved December 3, 2014.
- "NRC Administrative Letter 94-08: Consolidation of the NRC Region IV and Region V Offices" (PDF) (Letter to "All holders of operating licenses or construction permits for nuclear reactors"). July 13, 1994. Retrieved December 3, 2014.
- "Consolidation of two NRC western Regions effective on April 4" (PDF) (Press release). Washington D.C.: Nuclear Regulatory Commission. March 30, 1994. Retrieved December 3, 2014.
- Callan, L. Joseph (December 18, 1997). "Walnut Creek Field Office (WCFO) Closure Plan" (PDF) (Letter to "The [NRC] Commissioners"). Retrieved December 3, 2014.
- "NRC to close California Field Office in 1998" (PDF) (Press release). Washington D.C.: Nuclear Regulatory Commission. September 5, 1997. Retrieved December 3, 2014.
- "NRC California Field Office to close September 30" (PDF) (Press release). Arlington, Texas: Nuclear Regulatory Commission Region IV. September 23, 1998. Retrieved December 3, 2014.
- "NRC Administrative Letter 98-08: Availability of Revised NRC Form 3, "Notice to Employees" and Closure of NRC Walnut Creek Field Office" (PDF) (Letter to "All NRC licensees"). October 9, 1998. Retrieved December 3, 2014.