If you are looking to visit car museums in the USA, here is a list not to miss

here is a list of the top 10 in the world: http://www.edmunds.com/car-reviews/top-10/top-10-automobile-museums.html?articleid=122959 which completely agrees with http://smashingusa.com/12-definitely-worth-a-detour-car-museums-of-america/ and they agree that the Henry Ford, the National Corvette, and the Petersen are not to be missed and they suprised me with the Studebaker and the Natl. Auto museum in Reno (formerly the Harrah) http://www.automuseum.org/index.html

I'll start in one corner of the USA and work towards California,

in New Britain Connecticutt is a dealership, Papa's Dodge, that has Wednesday cruise nights - burnout contests, and a classic car museum http://www.papasdodge.com/dream-cruise.htm

the Gilmore in Michigan (doesn't open til May http://www.gilmorecarmuseum.org/ )
and if you get into Michigan see the Motorsports Hall of Fame http://www.mshf.com/ ,
and the Detroit Historic Museum's collection http://www.detroithistorical.org/
Benson Ford Research Center www.thehenryford.org/research/index.aspx

National Automotive History Collection   www.detroit.lib.mi.us/nahc/index.htm

The Wellborn Musclecar museum in Alexander City Alabama http://www.wellbornmusclecarmuseum.com/

The Microcar museum of Bruse Weiner in Madison Georgia (50 miles from Atlanta) http://www.microcarmuseum.com/

Mid America Motorworks, halfway between St Louis and Terre Haute on Hwy 57 http://www.mygaragemuseum.com/visitusmain.htm

the AACA in Hershey Pennsylvania http://www.aacamuseum.org/ ,

and if you got to Penn stop by Allentown and see http://www.americaonwheels.org/

you might try the Swigart in Huntingdon, PA http://www.swigartmuseum.com/index.html

down in Oklahoma is Phil Silva's Muscle Car Legends Museum http://www.pinemeadowcabins.com/muscle_car_museum.html

and the Punta Gorda muscle car in Florida http://www.musclecarcity.net/
Don Garlits Museum in Ocala http://www.garlits.com/
Sarasota has the 2nd oldest contiuously operated car museum; Sarasota Classic Car Museum http://www.sarasotacarmuseum.org/
the Indianapolis Speedway museum http://www.indianapolismotorspeedway.com/history/35204-Museum

The Lane museum is quirky and full of micro cars, it's in Nashville, and the Crawford http://www.carlustblog.com/2011/04/crawford-auto-aviation-museum.html in Cleveland are both in this top 10 list http://www.journeyetc.com/travel-guide/top-10-best-automobile-museums-to-visit-in-the-us/

While in the neighborhood of Illinois / Ohio, see the Packard in Dayton Ohio http://www.wrsol.com/usatravelguide/2009/12/bestcarmuseums-americaspackardmuseum/ .. .. Before you get too far from Nashville look for Hostetler's Hudson Auto Museum, in Shipshewana Indiana, thought to be the largest and most complete collection of Hudson, Essex, Terraplane, Railton, and Dover cars and trucks.

http://www.hostetlershudsons.com/ In DeSoto Kansas is Grandpa's Garage & Body Shop http://www.classicaldrives.com/50226711/in_a_town_called_desoto_grandpas_garage_features_old_fords.php Ya gotta see Speedy Bill's! It's the museum of American Speed in Lincoln Nebraska http://www.museumofamericanspeed.com/default.dlp

In the middle of South Dakota is the Pioneer Auto museum http://www.pioneerautoshow.com/
Near Denver Colorado is Terry's private Nash/AMC museum that he welcomes car people to http://www.pnwnash.org/museum

In Pheonix Arizona is the
Penske Auto museum: http://www.automotto.org/entry/jaunt-across-the-car-museums-of-america
plus the http://www.hallofflame.org/ Firefighters National Hall of Fame and 90 pieces of firefighting apparatus
plus the  http://www.martinautomuseum.com/
and the Streetcar http://phoenixtrolley.com/
and a Harley and motorcycle museum http://www.buddystubbshd.com/custompage3.asp?pg=museum01
In Tucson is the Franklin Auto Museum http://franklinmuseum.org/
and the http://tucsonhistoricdepot.org train depot that's been restored
In Chandler is the http://www.azrymuseum.org/ train and railway museum
In Scottsdale is the http://www.scottsdaleinternationalautomuseum.com/

Here in So Cal...
The Nethercutt http://nethercuttcollection.org/Museum.aspx ,
Justice Brothers http://justicebrothers.com/pages/racing-museum/r&m_racingmuseum_main.htm ,
Blackhawk http://www.blackhawkcollection.com/index.cfm?action=sales&tab=sales&control=bhc ,
Mullin Museum focusing on the Art Deco movement of auto design
http://www.mullinautomotivemuseum.com/the-museum.html
Lyon Air Museum in Santa Ana http://www.lyonairmuseum.org/
Day Family Classic Car Museum off Iowa Avenue in Riverside
the Riverside International Auto Museum  http://www.riversideinternational.org/
the Marconi Museum in Tustin http://www.marconimuseum.org/
and you ought to see Galpin Ford's display of Roth customs, the Mysterion and Orbitron, plus the Ice Truck http://galpinautosports.com/2011/02/g-a-s-custom-classics-wow-the-crowds-at-the-grand-national-roadster-show/  and  http://www.bangshift.com/gallery/Galpin-Autosports-gallery.html
in El Segundo Automobile Driving Museum 
New addition to So Cal is the Mercedes Benz Classic Center USA in Irvine http://www.mercedes-benz-classic.com/content/classic/mpc/mpc_classic_website/en/mpc_home/mbc/home/museum/overview_museum.html
A little farther North near San Francisco, is the Heidrick Antique Tractor and Hays Antique Truck Collections in one location, http://www.aghistory.org/

Up in Tacoma Washington, finally (I've been waiting 4 years) the LeMay museum is open http://www.lemaymuseum.org/

Here's a list of museums by state: http://www.team.net/www/museums/us.html but it's 5 years old, and might not be 100% accurate anymore
Here is a link to a list of lots of US auto museums http://www.digital-librarian.com/car_museums.html

And for a look at some museums before you go, to make sure it's worth the trip: http://www.remarkablecars.com/main/aa-museums/car-museums.html