SDRs are fun. I've picked up KOMO 1000 Seattle in Norway and Hawaii (and I used to think KIRO had the best AM signal in Seattle!) WSM. CFZM, WBBR and WLW cover nearly half of North America (WBBR and WINS could be heard in The Netherlands.) While full lower 48 coverage is impossible today, if these signals were anything I heard, it was definitely possible many decades ago (and a 500,000 watt WLW in the 1930s too? Holy cow!)