We can certainly get an idea of what was possible under the best conditions. The 1775 Beeline March saw companies of riflemen travel from Winchester and Shepherdstown VA the 600 miles to Boston in 24 days, at a rate that varied from 30 to 36 miles per day. But tht was in summer: so, presumably dry roads, young healthy guys, many hours of daylight each day, and no one in danger of freezing to death sleeping rough. When James Reeside began his business carrying mail between New York and Philadelphia in 1820, along what's now Rt 1, the run of about 94 miles started out as 23 hours, then dropped to 16, then to 12. But to get that sustained rate of speed ( between 4 and 8 mph) ,that was not a man on horseback: that was a coach and horses, with teams of horses typically switched at staging stations every 12 miles.

But there were many bad conditions.. Roads were generally terrible. The first well-surfaced and well-maintained road would be the Philadelphia -Lancaster Turnpike, not started until 1795. The rest were often not much more than trails. A group of Moravians traveling from Philadelphia to North Carolina in 1753 discovered that the ruts in one of the roads were very deep, and somewhat narrower than the wheels on their wagons. They had to stop for a day to get the wheelbases narrowed by a blacksmith, before they could continue. A French traveler on the Great Valley Road ( Now Rt 11) in Virginia discovered he was slowly battering his carriage to bits: he finally abandoned it to a blacksmith about halfway on his journey and continued on horseback. There was therefore a lot of variation as to how fast anyone could travel. Or, could want to travel. When staged coach lines became common on the National Road, in the early 1800's, a ride from Wheeling to Baltimore ( 285 miles) could take just 3 days, but often there were complaints at how the drivers loved to race along and didn't care for either comfort and safety- the coaches were nicknamed "spankers". So, each of the 90+ miles per day was very much felt in the bones of the passengers. For an un-staged, diligent but un-hurried journey of, say , a farmer and a wagon, 20- 25 miles per day was rather typical. But that was depending on conditions: how much daylkight: how much rain, ice ,snow; how healthy the team; And how many hills had to be climbed and descended. A long hill would require the team to be periodically rested ( and a good spot of a tavern would be at the top of a hill, providing water and aid) . Descent could be equally hard, as brakes were rudimentary and horses could be hurt or panicked with a wagon knocking into them. One solution was to jam the wheels with a pole and have the team drag the wagon downhill- but that would of course be dragged slowly.

Though there was not a firm rule as to the spacing of taverns, 12 miles was common . As I said, that's about how often a team needed to be changed for a stage coach. Taverns had stables for coach lines, fed and lodged people, and also were post offices. Mail routes ran on the main roads, and carrying letters was pretty profitable. Also as a part of that mail service would be newspapers and news: something incredibly important .

Lastly, someone could also catch a boat from New York to Boston and perhaps have an easier journey. Certainly, if they had a lot of goods to haul, a real cargo, that was more practical than a fleet of wagons. But that was also seasonal: anyone trying to make a trip in the North Atlantic in winter, or in hurricane season, took different risks than they would on the roads: but still took risks.

Warren Hofstra et al.: Great Valley Road of Virginia: Shenandoah Landscapes from Prehistory to the Present. Charlottesville: Univ Of Virginia Press, 2011.

Philip D Jordan: The National Road New York: Bobs Merrill, 1948.