Housing styles in South Central PA make it easy to guess an age of a home. If it's a ranch, my bet would be on 1960's to 1970's. Bi-level or Split level? Go with the 80's. Traditional two-story? 90's to present day. The good news if you are the owner of an older ranch home your house may be in demand. Many home buyers, from young to old, are considering one-floor living. The benefits may include heating and cooling costs, access, and upkeep.
Some advice: If you have a ranch house, keep it in shape. For starters, fix that old roof. Tear up the worn out carpet and finish those wood floors. Don't forget the kitchen and bathrooms. Every home and situation is different, so ask me or your local Realtor what they suggest before jumping into a bunch of projects.
Looking for a home or to sell the one you have? I'd be happy to talk to you about it.