DetroiterRob,

We live in a house built in 1970 or so. It is wired with aluminum branch circuits. The finished basement (probably finished sometime shortly after the house was built) has (or had, we just had it remodeled) some black NM cable. That at least gives a timeframe of when black NM was probably available.

The two circuits wired with the black NM, if they were added (as opposed to part of new construction), were probably added by the first occupant of the house. They power the garage lights and the basement bathroom.