CBC MW stations can be heard quite well in the northern states during
nighttime. The further south you go the likelihood of hearing these
stations decreases, since the range of a MW station at night is 1000
miles or so.

Huh? The skywave range is considerably longer than that! On a
portable radio with a strung up 75-foot wire antenna in Massachusetts,
I heard Salt Lake City & Texas (2,000 miles) on a regular basis all
night, and on a couple of occasions Los Angeles (3,000 miles). I have
easily heard Wyoming (~900 miles) here early summer mornings in the SF
Bay area using my *car radio* - and I doubt that a strong Canadian
station would take much more to get here than that one, especially if
it could use the grayline as the kicker.

Bruce Jensen