PDF VersionData is sourced from the Pennsylvania Department of
Environmental Protection. Map is designed to illustrate which counties
in Pennsylvania have experienced the highest amount of oil and natural
gas drilling activity. Actively producing well data is joined to individual counties to provide a count figure of active Marcellus wells within each area of interest. Data is provided as one record for each
The color gradient ending in dark red depicts counties with
the highest number of drilled wells. The year 2005 is used as a baseline as this period represents
the beginning of widespread natural gas drilling in the Marcellus shale
formation which underscores much of Pennsylvania.