Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.
Rig Count Interactive Map by Baker Hughes, an energy services company.
Shale Sheet Fracking, a Youngstown Vindicator blog.
The Ohio Environmental Council, a statewide eco-group based in Columbus.
Earthjustice, a national eco-group.
People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.
Concerned Citizens of Medina County, a grass-roots group.
No Frack Ohio, a Columbus-based grass-roots group.
Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.
Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.
Allegheny Front, environmental public radio for Western Pennsylvania.
Bradford County is No. 1 in Pennsylvania for Marcellus shale wells with 1,749 wells.
It is also No. 1 in Pennsylvania for violations, according to NPR's StateImpact Pennsylvania.Bradford has had 613 violations.
According to StateImpacr Pennsylavnia, the state has 7,725 active wells with 67 operators
Chesapeake Energy is No. 1 with 1,356 wells.
Across Pennsylvania, there have been 2,898 violations and fines of $3.5 million, NPS says.
No. 2 for wells is Tioga County with 1,076.
The rest of the Top 10 are Washington, 740 wells; Lycoming, 667 wells; Susquehanna, 592 wells; Greene, 562 wells; Fayette, 267 wells; Westmoreland, 245 wells; Butler, 228 wells; and Clearfield, 214 wells.
No. 2 for violations is Susquehanna County with 476. Lycoming is No. 3 with 474 and Tioga is next with 525 volations.
Click here to access the NPR site with all the details.