I have previously reported a listenable range on a truck radio for my ground mounted AM system system as being 1 mile with fading at 1.3 miles. Today, while on an errand, I checked range again and it was solid listenable out to 1.8 miles on my truck radio and could be heard with flutter and noise 2.3 miles away (that's as far away that I drove). Though this is impressive for a part 15 AM system the actual range for in home listeners is not known but it is most probably much less. Someone with a good receiver and an outdoor antenna could probably receive the signal at two miles plus.
What has changed? Since my previous check we have had quite a bit of rain and the ground is moist but the field strength checked with my monitoring system hasn't changed. The other change is that I was previously using a modified Ramsey AM-25 but am now using my "high efficiency" transmitter which delivers 86 mW to the antenna system with 100 mW DC in. This doesn't explain the change in range however since the modified AM-25 delivers about the same power to the antenna system.
The other encouraging observation is that I have not tuned the antenna system in over a month and the field strength remains the usual so it appears to be stable.