Cavalry impacted the population by helping American soldiers win and takeover Native American tribes. This resulted in the Americans being able to takeover land and have more power than their opponents.
Cavalry chased down the Apache Tribe during Victorio's Resistance. In 1885 and 1886 the Cavalry spent over a year on the trail of Geronimo.
Cavalry was used into the era of gun POWDER Cavalry helped troops advance in battles to the point where armies could focus more on modern technology.
Currently cavalry is not being used by military, but there are lots of mAchinized units to do the same things as cavalry once did.