Thanks to the several of you who replied to my inquiry about why 1110 was DA-D. If they applied for that facility today, they might likely have to protect Bay Minette AL. However! This station, originally known as WBCA, was on 1150 1 kw D back when WALT became a 10 kw DA-D station. WBCA did not move to 1110 10 Kw D until much later, around 1967. That was long after WALT was 10 kw.
I know of stations along the coast that operate DA-D just to redirect signal over land/population instead of sending it out into the open water. Thought maybe that was the reason for the 3 tower system, as it seemed to me WBT was too far away to matter in groundwave terms.
I have lived on the Alabama gulf coast for most of my 69 years, and have frequently DXed daytime at the shoreline. There we've never had any trouble hearing Tampa Bay area AM stations... 620 970 1380 roared in ... could also hear the lower powered ones like 1520 1590 680 1040 820 1550 1300. Never could hear 1250 until the last few years; I figured they changed their daytime pattern as they come in well now. Never could hear 1110 even before the nearby Bay Minette station went to 1110. Heck, I could even hear 1340 Clearwater ... oh and 1470 is an easy catch too. But no 1110 ... and 1010 doesn't make it up here either, obviously because of DA. The 570 station barely makes it ... we used to have 570 in Biloxi MS but it's gone now. The 860 station is there, but it's tough to pick it out with WWL 870 next door.