Maryland’s governor, Larry Hogan, on Tuesday signed into law a bill that bans hydraulic fracturing in the state. The move comes a week after the state’s legislature passed the bill.

Maryland currently has no fracking activity inside its borders, leading many to label the move political—that is, a play to constituents without much consequence. But the western part of the state sits atop a portion of the Marcellus Shale, and industry for a while now has considered the prospect of drilling in the state.

Environmentalists praise the governor’s actions, but opponents of the law defend fracking and its safety. They also point to the economic opportunities that could be lost as a result of the ban. The Marcellus is the largest source of natural gas in the United States, and the region has played a key role in the country’s recent energy boom.

Maryland becomes the third state to ban hydraulic fracturing, the first being Vermont and the second New York. Vermont banned the practice in 2012, New York in 2015. One difference between Maryland and its two predecessors: Maryland is the only state of the three with known natural gas reserves.

The law goes into effect October 1, when the state’s current moratorium on fracking expires.

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