The JMT is one of the most famous trails. It traverses the sierra in California from Yosemite to the highest point in the contiguous US at Mount Whitney down South.
It is popular and shared with the Pacific Crest Trail. Some High Route versions might fit more trekkers looking for more remoteness but I still highly recommend it as the sceneries are world class and the trail in really good shape. It was also one of my first longer distance treks and brought a lot of learnings / forgiveness and it mesmerized me the whole journey.