[skr]

Genesis 4 But before they lay down, the men of the city, even the men of Sodom, compassed the house round, both old and young, all the people from every quarter: 5 and they called unto Lot, and said unto him, Where are the men which came in to thee this night? bring them out unto us, that we may know them.

Apparently the city ran out of righteous men, aside from Lot and his family, that up to then had spared it from destruction as per Abraham's previous pleadings to God.

[Cronos]

but i’m sure there have been other places through the ages that have been devoid of righteous people (Castro street in San Francisco comes to mind)