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.
A new study by researchers at Penn State University's College of Agricultural Sciences says that Marcellus shale drilling areas have a significant impact on the local collection of state taxes in Pennsylvania.
Sales tax collections in counties with more than 150 gas-oil wells rose nearly 24 percent between 2007 and 2011, compared to an average decrease of 5 percent in counties with no Marcellus wells, the researchers said.
Sales tax collections dropped in only 3 of the 23 counties with more than 10 Marcellus wells, compared to decreases in 22 of 32 counties with no Marcellus drilling, the report says.
Sales tax collections boomed the most in Bradford County (50.8 percent), Greene County (31.4 percent) and Susquehanna County (27.4 percent), three of the top six counties for Marcellus wells.
The data supports anecdotal accounts of drilling increasing local retail activitiy, Penn State researchers said.