Complex sentence: At the turn of the century, the population surge plateaued and industry began to stagnate; it was only after World War I that the local economy was able to recover, the result of a number of manufacturing companies setting up shop in the village.
Split into simpler sentences: At the turn of the century, the population surge plateaued and industry began to stagnate. It wasn't until after World War I that the local economy was able to recover, the result of a number of manufacturing companies setting up shop in the village.