Baltimore sits on the Patapsco River near the Chesapeake Bay, and tens of thousands of attached rowhouses line its streets. Shared walls, alleys and old basements connect one neighbor's pest problem to the next.
Baltimore became an independent city under the Maryland Constitution in 1851, which is why it belongs to no county. The 2020 census counted 585,708 residents on about 81 square miles of land. The city sits on the Patapsco River close to where it empties into the Chesapeake Bay, and the ground climbs from sea level at the harbor to about 480 feet near Pimlico in the northwest. Wikipedia puts the July average near 80.7 degrees.
Housing here is mostly rowhouses, many faced in brick or formstone, and the Inner Harbor anchors the commercial core around Camden Yards. Warm summers, a harbor, old basements and shared plumbing suit cockroaches, rats and mosquitoes. Termites and carpenter ants have older wood and damp spots to work with, and apartments, hotels and dorms give bed bugs plenty of travel routes.