where do i get information on a vacation to western usa?

i need maps and information about national parks and historical sites to see

Google tourism + the state you want to visit. In my case, I am going to Arizona in April. I went to Arizona’s official tourism website and ordered a guide. It’s already here. You can do that for as many places as you like. The guides are free, and contain a lot of useful info.

For national parks, they have a website with all of them, or you can see the sites for just the ones you’re intrested in. I think it is usparkservice.gov. (Not sure, just google and you shall find.)

Google is your friend!