2nd Regiment, Pennsylvania Infantry (3 months, 1861)
This regiment was organized at Harrisburg April 20, 1861. It mustered out July 26, 1861. 
Companies in this Regiment with the Counties of Origin
Men often enlisted in a company recruited in the counties where they lived though not always. After many battles, companies might be combined because so many men were killed or wounded. However if you are unsure which company your ancestor was in, try the company recruited in his county first.
The Second Regiment was recruited in:
Company A - many men from Chambersburg, Franklin County
Company B - many men from Chambersburg, Franklin County
Company C - many men from Thomas, Franklin County
Company D - many men from Bloomfield, Perry County
Company E - many men from Gettysburg, Adams County
Company F - many men from Columbia, Lancaster County
Company G - many men from West Chester, Chester County
Company H - many men from Bellefonte, Centre County
Company I - many men from Harrisburg, Dauphin County
Company K - many men from York, York County
National Park Service, The Civil War Soldiers and Sailors System, is searchable by soldier's name and state. It contains basic facts about soldiers on both sides of the Civil War, a list of regiments, descriptions of significant battles, sources of the information, and suggestions for where to find additional information.