For the past 30 years or so I have written about issues relating to sub-state unit regulation of the extractive industries, in general, and oil and gas exploration and production activities specifically.   By sub-state unit, I intend to aggregate governmental entities such as counties, parishes, municipalities, towns, townships and boroughs, many of which exercise general police power to regulate for the protection and/or enhancement of the public health, safety, morals, and general welfare. Indirect sub-state regulation of the extractive industries dates to the first decade of the 20th century.   People tend to also forget that while state administrative agencies were regulating oil and gas and mining operations, it was sub-state units in Kansas, among other places, that adopted statutory pooling ordinances to prevent over-drilling within urban areas.   After a multi-decade period of quiescence relating to sub-state regulation of oil and gas operations, such regulation re-appeared with the application of horizontal drilling and hydraulic fracturing technologies to various shale formations throughout the United States.