America is much larger, and much more inland than Western Europe, so horses are even more valuable in the American Middle Ages than the European Ages. Horses are expensive to keep, but they are worth their weight, and the value of horses has resulted in intensive breeding for the animal, especially in places like Kentucky and Texas. In fact, many are quite specialized for speed, luggage capacity, and of course, warfare.
Heavy cavalry is the most commonly used tactic in the forest zone of the east, where the regions are vast and not very centralized, and rule is enforced by a ruling warrior class. Horses must be big and strong to withstand battle and the weight of their armored riders, so the midwest is able support horses with the surplus of hearty grains, and the south is able to use the longer growing season and diverse crops to their favor. The Ohio River valley has access to crops, metalworking, and generations of horse breeding that has allowed Ohio to become the most powerful feudal realm on the continent.
For the most part, eastern knights prefer the sun-blocking morions on helms, and the lither saber as for sword-fighting. The more mineral-wealthy north has heavier armor than the south, which may supplement their mail with and arms with leather and wood.
"Templar" is a catch-all term for the heavy cavalry utilized by the Hydraulic Empires of Deseret and California, who's soldiers are theoretically supposed to be untitled and tied to the state, and usually wage war on behalf of their faith. The consolidated wealth has access to the weaponry and horses required to be a knight, but anyone who wishes to be a Templar has to be tested and buy their way in. (This keeps the armies pressed and focused.) In theory, Templars are supposed to be celibate (And Easterners spread rumors of homosexuality), but somebody is keeping the brothels of the deserts open.
In times of peace, warlords will keep their skills sharpened with tournaments held in most major cities. Jousting is the largely the most popular, although melee will take a variety of forms. In the more Northern regions, there's more of an emphasis on padding up and jumping straight in. Tournament fighting in the South is more about speed, since heavy armors can be uncomfortable in the hotter climate. It's for this reason the Southern nations will hold most of their major tournaments after the harvest season is over, in December and January. Although most of the competing knights are from below the Mason Dixon, everyone from Non-Denominational world is invited. Well-off knights from the north will gladly take a leave from their snow-ridden homes to test their skill in January's Super Bowl Tournament. (The at the behest of the Church, nobody performs on Sunday) The event is not only a big deal for competitors, but for merchants who can sample consumers from all over the continent. The tournament will even present theatrical shows starring characters like Shrek, Snoopy, or Spiderman. The Delmarva Peninsula is home to some of the United States of America's mounted warriors, and they participate. Along the western frontiers, however, herdsmen abhor the pageantry and wastefulness of knights. Their answer to the tournament is the Rodeo.