Regional salvage isn't the same everywhere, because the buildings aren't. What a region built, when it built it, and what happened to that stock since all shape what its salvage yards hold now, so the trade has a distinct regional character.
East, Rust Belt, West
New England and the older East salvage the deepest history. This is the country's oldest building stock, so its yards run heavy on early material, colonial and Federal hardware, Victorian ornament, along with cold-climate features like storm windows and tight hardware. The Rust Belt salvages the industrial century. The mill towns and manufacturing cities built vast amounts of industrial and commercial fabric, and as that economy contracted, a great deal of it emptied and came down, so Rust Belt salvage is rich in industrial lighting, factory hardware, and commercial fixtures, often in quantity. The West salvages a younger, faster-grown stock. Much of the West grew mainly in the twentieth century, so its yards run to Craftsman, Spanish Revival, and mid-century material, and lighter on early Victorian hardware.
None of this is absolute, since catalogs standardized much of the country and material travels, but the tendencies are strong enough to shape what a yard in each region is likely to hold.
Salvager's Note: Matching a specific house? Region helps. Early Victorian and colonial hardware is easiest to find out East; industrial pieces run heavy through the Rust Belt; Craftsman and mid-century fittings are the Western strength. A part that suits one region can look wrong in another.