Population change varied notably across four Pennsylvania counties and in nearby cities and towns that are home to a majority of the state’s Marcellus Shale development from 2000 to 2010, suggesting such trends are not linked to the level of economic activities in the areas examined, according to a new study.

The Center for Rural Pennsylvania, a bipartisan agency of the state’s General Assembly, commissioned the first-of-its-kind study to analyze the relationship between population change and the economic activity that the oil and gas industry has created.

The study examines in depth two regions where Marcellus Shale development has been focused: Bradford and Lycoming counties, and to a lesser extent 10 surrounding counties in the northern part of the state, and Greene and Washington counties, as well as four surrounding counties in the southwest part of the state.

Based on data from the Pennsylvania Department of Environmental Protection, the four study countries account for half, or 3,376 of the 6,833 unconventional wells that have been drilled in the state. In all, the study said 90% of all wells drilled in Pennsylvania through June 2013 are concentrated in just seven counties.

The study found that between 2000 and 2010, Pennsylvania gained more than 400,000 residents, while heavy population losses in Lycoming and Bradford counties were offset by gains in surrounding counties. In the southwest, Greene County lost residents, while Washington County gained in population over the decade.

The state’s overall population growth appeared to coincide with the uptick in activity associated with the Marcellus Shale that began to slowly increase around 2005 or so, according to the study. From 2000 to about 2006, Pennsylvania’s annual population growth of 1.6 residents per 1,000 lagged far behind the national rate of 10.3 per 1,000. But from 2006 to 2010, that rate nearly quadrupled when the state began adding six residents each year.

Variables in the northeast and southwest counties, however, led the center to conclude in its study that the “patterns of population change over the decade and across counties in the state of Pennsylvania vary and show little relationship to the extent of unconventional natural gas development in the Marcellus Shale.”

Counties in the north gained just 5,600 residents, as a loss from 2000 to 2006 was slightly less than the gain from 2006 to 2010. In the southwest, although Washington County, where many oil and gas companies have relocated their regional headquarters, gained 5,000 residents from 2000 to 2010 (see Shale Daily, Jan. 3, 2011), population loss in Greene and surrounding counties showed that 83,000 residents left the area.

The latest study from the center is part of its Marcellus Shale Impacts Project, which examines population and socioeconomic changes brought on by the state’s shale boom.