Looks like gravel to me
Panaracer Gravel King, Donnelly X'Plor USH, and whatever is made by Bontrager are all popular options for the local Minnesota/Iowa gravel, which is similar to what you've posted.
Do you know what size wheels you have on the bike? That could make a difference in tire availability.
Props to you for doing 20 miles a day on that stuff - that is some serious riding!