City Directories have always been one of my personal favorite set of genealogical records. MyHeritage now has the best collection, and the best searching technology (ie: do an address search to see the history of everyone at the same address) for city directories.
I received exciting news just now that the entire collection will be free to access at from December 2-7, 2021.
Here's more about it from MyHeritage:
The U.S. City Directories collection contains over 561 million records in 26,000 public U.S. city directories published between 1860 and 1960. They typically include names, names of spouses, addresses, occupations, and workplaces, which makes them a rich source of information about family members in the United States — especially as an alternative to missing or destroyed census records. The MyHeritage collection is especially valuable because of its advanced indexing and multiple record consolidation, which make it much easier to find what you’re looking for and track your ancestors’ progress over time.