The Appalachian Trail is a legendary route in the United States, with more than 3 million people visiting it every year and over 3,000 people attempting a full thru-hike of the entire footpath in a single year. There are other famous thru-hikes throughout the country, most notably the Pacific Crest Trail and the Continental Divide Trail, but those three might not be the most ideal for you.
YouTuber Greenbelly dove into the different major thru-hiking trails throughout the country, ranging from some of the easier, more built up trails to the much more difficult remote trails like the Hayduke Trail.
This video is a good way to get you to start thinking about your next massive adventure, but further research on each trail is obviously necessary before you hit the trail.