Complex sentence: By 1918 the village of Wilmette had increased its population 5,000 from a population of only 1,500 twenty years earlier and a new village hall was constructed to meet Wilmette's growing needs.
Split into simpler sentences: By 1918 the village of Wilmette had increased its population 5,000 from a population of only 1,500 twenty years earlier. A new village hall was constructed to meet Wilmette's growing needs.