Complex sentence: Downtown has had numerous new small businesses move into the area, and several organizations; one of which started right in Downtown itself; the Missoula Downtown Association (MDA) has been a large organization lately in Missoula.
Split into simpler sentences: Downtown has had numerous new small businesses move into the area, and several organizations. One of these organizations which started right in Downtown itself; the Missoula Downtown Association (MDA) has been a large organization lately in Missoula.