Complex sentence: In fact, it was the railroad that established the tiny hamlet of Johnsonville as the most important industrial town in all of Pittstown in its time, thanks to its close proximity to the Hoosic River, the largest tributary of the Hudson River.
Split into simpler sentences: In fact, it was the railroad that established the tiny hamlet of Johnsonville as THE most important industrial town in all of Pittstown in its time. This is because of its close proximity to the Hoosic River, the largest tributary of the Hudson River.