Travel Information for Johnstown:
Fly to a Major Airport
... and Connect to Johnstown by Rail
On first look, it would appear that the easiest route to Johnstown without renting car is Pittsburgh. It turns out, however, that routing through Pittsburgh generally requires an overnight stay in Pittsburgh.
Fortunately, Pittsburgh is not the only major airport with rail connections to Johnstown. Philadelphia, Baltimore Newark and JFK all have rail connections to Johnstown. In addition, Chicago has an overnight train connecting at Pittsburgh to Johnstown. The train route through Pennsylvania is probably the most interesting on the East Coast, so that part of the trip should be quite enjoyable.
Routing through Pittsburgh. While Pittsburgh has the closest major airport, the problem is that the train departs Pittsburgh at 07:20. There are later busses, at 09:00 and 11:00.
On the return (Johnstown to Pittsburgh), the train arrives 20:05 and the busses at 18:25 and 21:15.