There's a BUNCH of American field guides for varying skill levels.
Beginner guides include:
The Audubon guide, which is color coded with photos, and it's known for being BAD. These are broken down into eastern and western versions.
The American Bird Conservancy guide, which is arranged oddly, with habitats, behavior, and bill shape being the sorting criteria.
The Peterson guide, which has illustrations separate from the text, with MANY birds per plate, and it has arrows pointing to the diagnostic features. These are also broken down into eastern and western versions.
Kaufman, which might be a good guide for someone just trying to sort things out. It's got photos, but they're photoshopped to look more representative of all the members of the species. The range maps are good too.
The Golden guides, which I have never used.
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More advanced guides include:
Sibley, which a lot of people SWEAR by. The problem I've had with Sibley is that you have to know what you're looking for to be able to find it. I use it more for double-checking ID's than for trying to figure out something totally unfamiliar. He's also got eastern and western guides, which are smaller and have fewer species.
National Geographic, which is what I find myself using most often. There are state editions which I haven't checked out, that have stuff more specific to the region you live in.
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The curse of American field guides is that there are close to 800 species recorded here, but probably 500 of them are NEVER going to turn up where you live. But every field guide has to include Alaskan rarities, Mexican rarities, Caribbean rarities, and so forth. In American birding, range maps are CRITICAL. I'd definitely go buy or print out a state, county, regional, or park checklist, and lean on that when trying to figure out something confusing.
You might go to the library and check out their field guides, and see what you like.
To BUY, I'd probably get Kaufman and National Geographic or Sibley, but you may like a different combination. :shrug:
Edit:
Here's your state National Geographic guide, so maybe this and Sibley? :shrug:
http://www.abasales.com/index.php?main_page=pubs_product_book_info&cPath=110_111_150&products_id=2113