7th Regiment, Pennsylvania Infantry (3 months, 1861)
This regiment was organized at Harrisburg April 23, 1861. It mustered out July 29, 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 Seventh Regiment was recruited in:
Company A - many men from Pittsburg, Allegheny County
Company B - many men from Allegheny, Allegheny County
Company C - many men from Fredonia, Berks County
Company D - many men from Pleasantville, Berks County
Company E - many men from Allegheny, Allegheny County
Company F - many men from Pittsburg, Allegheny County
Company G - many men from Reading, Berks County
Company H - many men from Boalsburg, Centre County
Company I - many men from Lewistown, Mifflin County
Company K - many men from Pittsburg, Allegheny 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.