What are symptoms of spider bites in the u.S.?

Depends. Anything from minor itching and redness, to crusting, oozing and in a few cases severe skin and soft tissue breakdown. It depends upon the species. See: << http://www.Webmd.Com/allergies/ss/slideshow-bad-bugs?Ecd=wnl_aaa_060412 >> for a pictorial view.
Spider bites. Spider bites can have variable appearances. It might cause a pink or red bump with no symptoms. Or it could itch or be painful. Venomous spiders may cause significant pain radiating far from the site, cramping, sweating, necrosis of tissue or worse if there is an allergic reaction.