I'm about 50 miles NW of Chicago. Wall outlets were vertical until 1970 or so, then horizontal. To me, installing it horizontal shows it's new wiring, but if I'm adding one outlet to an old room, I match the height and orientation. NM is allowed in McHenry County and City of McHenry, BX is allowed in Crystal Lake, and almost all other nearby towns require conduit.
The policing of permits is loose here, so NM is routinely patched in by carpenters/handymen. I personally love the requirement for conduit because on permitted work, it keeps the amateurs away, and it's profitable. If you're running 8 wires in a 50' open run, it's quicker and cheaper than other methods. It's easier to add a circuit to split up existing circuits, or add another wire for ceiling fan control, but not so hot if you want to move a box with 4 pipes over 4" in existing construction.
Dave
