We vacationed in the northeast US this fall and I'm interested in derivations of suffixes that appear in town names. Burgh-boro-bury were easy to find but I haven't been able to find the meaning behind "scot" and "kassit" in place names.

Sounds like you've been up near my home town in Northern New York--everything there is borogh or boro or kassit or scot (or lake or falls lol).

Many of these endings are from Native names for places, or Dutch from early settlers.

However, to find out their meaning we'd probably have to know what Native tribe named the place, and find a dictionary. You might have good luck looking up the places themselves. Some places have websites that tell their history and name meaning.