I was watching the latest epsiode of Matt's Off Road Recovery and in the first 20 seconds of the video Matt is mentioning the lower 48. He says that viewers from New Zealand asked him what the lower 48 means, and he doesn't know. In fact, nobody in his crew knows........ That's weird. I'm not from the US, but even I know what it means. Watch the first 20 seconds of the video:
What's more appropriate is the lower contiguous 48 as we have places like these that are part of the "lower 48" but that you can't get to from here.
Getting to Angle Inlet requires driving a gravel road, then stopping at Jim's Corners to phone US Customs in Warroad, MN. Angle Inlet has the northernmost road in the contiguous 48 states. I've never driven it though.