A lot depends on terrain. That being said, I reliably get digital stations (100% signal strength) from two different cities. One city is 45 mi away and the other one is 70 mi.
I have a Channel Master CM 4228 antenna + CM 7777 V/U preamp, installed on a mast about 25-30 ft above ground, and I live on a hill top. There are other good antennas besides the CM 4228 (example: the Antennas Direct 91XG), but the 4228 works well for a lot of people on this forum.