Leetsdale is a borough in Allegheny County, Pennsylvania, along the Ohio River and is part of the Pittsburgh Metro Area. The population was 1,232 at the 2000 census. The town has gained a certain popularity due to its name, a coincidence with Leetspeak, a common Internet sociolect.. Leetsdale at one time had a formidable industrial manufacturing base with a Bethelehem Steel mill that closed in the late 1970s.