If you are looking for a guided trek of a month or longer, then there might be such commercial treks organized for travel in Nepal, New Zealand, or in the Andes. I do not know of any such hikes to recommend, but I would start there.
Here in the USA I do not think such guided month-long treks exist in a form where you could just sign up, pay and go. There are USA outfitters who will offer guided hikes, in the Sierras for example, but probably not for a whole month. As commercial enterprises, they will be advertising on the internet.
If you are wanting to organize your own month long wilderness trek in the USA, then you will need to do a large amount of planning. The most common such long hikes take place on the Appalachian Trail (AT) or the Pacific Crest Trail (PCT).
You would be required to provide your own gear, food and transport, but several thousand people successfully complete such long self-organized hikes each year and there is a lot of information on the internet about how to plan and execute such a hike.