Complex sentence: Burlington, Vermont (pop.42,217,2010 Census) is by far the largest city on the lake, having a larger population than the 2nd and 3rd most populated cities/towns (Plattsburgh, New York, and Colchester, Vermont, respectively) combined.
Split into simpler sentences: Burlington, Vermont (pop.42,217,2010 Census) is the largest city on the lake. The 2nd and 3rd most populated cities/towns are (Plattsburgh, New York, and Colchester, Vermont, respectively) combined.