I'd like to backpack during my trip to the states, any suggestions? Perferrably would like to cover most of the states, visit game parks and summer fairs. Thanks!
Game parks? Don't recall having seen such things in my various travels in the US - although there are wild life refuges and reserves where at times of the year there may be large numbers of migratory birds. You can (or could) see buffalo in Yellowstone National Park.
Cover most of the states? You obviously have LOTS of time.
There are various city/community festivals as well as county and state fairs. Most county and state fairs probably are in the late summer / early fall - since agriculture was often a large component of such events.
If you want to do hiking, national and state parks are the way to go - private lands are often closed. There are long distance hiking opportunities such as Appalachian Trail and others. Check, some national parks are free, some national parks/monuments and many state parks charge a fee. National forest lands are open to public, although camping is often restricted. Wilderness areas and other special designation areas are often permit-use only.
You do realise that the US is as big as China? And that there are 50 states (48 on the mainland)? So covering 'most of the states' is a bigger task than covering most of the provinces of China.
Also, depending on when you go (I assume you're going in summer), many people in the US will be on holiday, so most of the parks (both amusement parks and National Parks) will be very crowded and accommodation will be difficult to get and/or expensive.
This link will give you a good overview to decide and plan a trail. You will need a car though. http://www.nps.gov/
You can consider going to Grand Canyon National Park, Petrified Forest, Saguaro National Park which are all in Arizona.
Yellowstone in Idaho or Montana.
I met a group of Australians some years ago who bought a car and traveled around the States for a couple of months. They crashed at my place while they explored Seattle and the surrounding area for a week or so.
If you know that you will visit at least two national parks consider getting yourself an annual pass.
To save on accomodation and the opportunity to mingle with more locals consider:
www.globalfreeloaders.com
www.coachsurfing.com
www.hospitalityclub.org http://joomla.servas.org/
If you are traveling between east coast locations consider taking buses between the different Chinatowns, the cost can be as low as US$10.00 one-way: www.chinatown-bus.com