In Europe, during the 18th and 19th century, the kings and emperors decided that they wanted grand esplanades and straight roads so they could have nice parades

In Europe, during the 18th and 19th century, the kings and emperors decided that they wanted grand esplanades and straight roads so they could have nice parades, preferably between some nice castles or parks. So they just demolished everything that was in the way. But hey! Marching in cool hats! I am not sure about U.S, but my guess is that the cities started to grow a little bit later, the people probably looked at the European kings cool-looking roads, and probably decided that they could do even better and just went for an even cooler looking grid instead just some avenues scattered here and there!