Read the attachment I sent. There is no non-directional 50 kw station above 1210 in the US. 1220, 1570 and 1580 are Mexican 1-A clears, with 1220 and 1580 being allowed limited use in Canada and highly directional use in the US. 1540 is a Bahamian clear channel.
The others are all highly directional. In fact, WTOP had to move its successful format from AM to FM a few years ago because it no longer covered the growing DC market because of its lousy frequency and highly directional antenna.
The former 1-A's are 640, 650, 660, 670, 700, 720, 750, 760 ,770,780, 820, 830, 840, 870, 880, 890, 1020, 1030, 1040, 1100, 1120, 1160, 1180, 1200, 1210.
And the Class I, II, III and IV were reclassified quite a while back and are no longer identified that way. They are now A, B, C and D classes:
AM Station Classes, and Clear, Regional, and Local Channels The chart on that page shows the former classes of the primary 1-A and 1-B stations under the old assignment system (not including the "breakdown" of the 1-A clears initiated in the 70's to provide enhanced rural radio service.)