It's a topic people ask me about more than perhaps any other: if you're planning a cross-country road trip, what route should you take?
It's also a topic where you'll find a lot of bad information out there. You'll hear from people who have done only one route, whose opinion of the other choices is based on hearsay or speculation. People who have done it once or twice, possibly in a hurry, whose experience is skewed by conditions that don't apply to your trip. Basically, it's an area where there are more opinions than experience.
Nowadays, some folks will simply do whatever their GPS tells them to do, like mindless zombies. I neither have nor want a GPS unit in my car. I'd rather enjoy the trip. GPS can't tell you why you should go one way rather than the other.
So, I'm going to go over your choices. Obviously all of the possible trips are well beyond the scope of a single post, so I'm starting with the most common (in my experience) topic: driving from the Northeast to either Las Vegas or Los Angeles, or vice-versa.
I have driven everything I'm writing about here, multiple times. This is first-hand reporting.
Southern Route
For the Southern Route, take the Pennsylvania Turnpike to I-70. I-70 takes you west to St Louis, where you pick up I-44 to Oklahoma City. There, get on I-40 west to Arizona. If you're going to Las Vegas, you then take US-93 the rest of the way (not the only choice, but that's a topic for another post). Or, proceed on I-40 into California and then I-15 to Los Angeles.

This is the best route. Although Ohio, Indiana, and Illinois aren't very interesting, they go by pretty quickly. From St Louis on, though, you're more or less following Historic Route 66 – you could spend your life exploring all the wonderful stuff on this route.
Toward the end of Missouri, Route 66 briefly deviates from the Interstate route. You can take a leisurely side trip by following this route through Joplin into Galena, Kansas, and then down into Oklahoma where you rejoin the main route on I-44 (which is also the Oklahoma Turnpike).
Proceed through Tulsa to Oklahoma City, either of which offer a great stopover. In Oklahoma City pick up I-40.
There are so many Route 66 sites and other stops on this route that you'll never get to them all. You'll cross from the wonderful-smelling Oklahoma into the dry plains of Texas. In Groom you'll see the “largest cross in the western hemisphere” on the side of the highway. Amarillo is your next oasis of civilization, if you're looking for a place to stop or some good food.
Then you get the beauty of the New Mexico desert. If you didn't stop in Oklahoma or Amarillo, Tucumcari (pronounced like "two come carry") is a Route 66 town, a traditional stop for explorers, offering dirt-cheap, clean, and nostalgic motels that will make you weep for the good old days.
You can explore the ghost towns of Glenrio, Texas, and Cuervo, New Mexico, if you're into that sort of thing. Both are right off the Interstate, so no side trips are necessary.
The next oasis of civilization is Albuquerque. It really is the only opportunity you'll have for anything like Starbucks or Applebee's for some time, so you'll probably want to stop here for a bit. After that, Gallup is another Route 66 town offering some amount of civilization.
After crossing into Arizona, you can take a quick car tour of Petrified Forest National Park, which you can do in a couple hours. Then it's on to Flagstaff, your next real oasis of civilization. On the way are many interesting Route 66 stops, including Two Guns, Twin Arrows, and Winslow, where you can stand on the corner from the Eagles song “Take It Easy.”
In Flagstaff, you can find civilization, overpriced hotels – and a side trip to the Grand Canyon. The South Rim is 80 miles from Flagstaff.
Kingman, Arizona is only barely an oasis of civilization, but it's the best you're going to get at this point. From here, if you're headed to Vegas, you can head up US 93 over the Hoover Dam. Or, stay on I-40 into California, through the Mohave Desert to I-15 and on to Los Angeles.
If you get the impression from how much I have to say that I love this drive, you're right. When someone says to “imagine your favorite place,” I don't think of a single place, I think of driving this route. I could write an entire book about how great this drive is, and I would love to. If you're planning your first cross-country road trip, this is the route you need to take. Provided you do it right, I promise that you will henceforth divide your life into “before” and “after” you made this trip. I do.
The Confederate Variation
Another option is to go from the Pennsylvania Turnpike onto I-81 South, picking up I-40 in Tennessee. This is the same as the Southern Route, changed in the east to head through Virginia, Tennessee, and Arkansas, in what I call the “Confederate Variation.”

This route takes longer and is less interesting than the eastern part of I-70. It doesn't make a lick of sense unless you want to stop someplace along the way.
Candidates include: Great Smoky Mountains National Park in Tennessee; Nashville, if you're into country music; and Little Rock, where you'll find the Bill Clinton Presidential Library, which is definitely worth a stop.
West Virginia's Mongahela National Forest is a quick side-trip away from this route, if you want to go camping. (The campgrounds at Lake Sherwood have hot showers!)
You'll rejoin the main Southern Route in Oklahoma City.
Middle-America Route
For the Middle-America Route, you pick up I-70 in Pennsylvania and stay on it all the way to its end in Utah, where I-15 South will take you to Las Vegas or Los Angeles.
This is the fastest route. It's not as life-changing as the Southern Route, but sometimes you need variety, and instead of the desert, you get the prairies of the Midwest and the Rocky Mountains.
When you get to Denver, Rocky Mountain National Park is less than two hours away as a side trip. If you've never had the opportunity to drive your car above the clouds, take this side trip – but only in the summer.
The mountain pass west of Denver is a marvel of civil engineering, and takes you to very high altitudes: in the winter, this is not the best route to choose. If you choose this route in winter, or even spring, check the local weather forecasts carefully before leaving Denver. You can still bail out: take I-25 south to Albuquerque and join the Southern Route. Tire chains are mandatory here in winter – if you don't have them and know how to use them, this is not where you want to be in January.
Once you cross into Utah there are several side trips to consider. Arches National Park is an easy drive from the Interstate, and Canyonlands National Park isn't far from there (but less interesting as a quick car tour). Bryce Canyon is two hours from the Interstate but well worth it. Zion National Park isn't even that far, but is less interesting as a car tour. If choosing only one, go with Bryce Canyon.
In Utah, I-70 goes though a long stretch of nothing: no gas, food, lodging, towns, cows, or anything else at all. Make sure to fuel up beforehand; there are signs to warn you (a lot of people run out of gas here). In the middle of this desert wasteland, the 75mph speed limit inexplicably drops to 60. It's not well-posted, and the highway patrol revenue agents may well be there to greet you. It's the speed trap to end all speed traps, and the out-of-staters are the targets. I have a speeding ticket as a souvenir that I wouldn't have gotten had I known the speed limit changed. Be careful here.
In the Utah desert – which is strikingly beautiful – I-70 ends, and I-15 will take you to Las Vegas and on to Los Angeles. If you enjoy scenery, you will love it. There are places to stop, to rest or sleep or take pictures, but few services, so be prepared.
The Bad Route
If you ask Google Maps to take you from New York to Las Vegas with no further instructions, the first route it will give you is I-80 to I-76 to I-70 to I-15. I'm not going to waste the time to make a map of this route, because under no circumstances should you ever consider using it. The only reason I can imagine why Google brings it up first is because someone at Google hates you, and gets a kick out of imagining you choosing this route and having a miserable trip. If your GPS also brings up this route, I can only think it's a punishment for using a GPS to plan a trip like this.I-80 through Pennsylvania is fine, but from Ohio through Illinois, it's a miserable journey of toll roads with Nazi-like enforcement of 65mph speed limits, with nothing of interest on the way. The toll roads are turnpike-style, so casually getting off at an exit means paying the toll, then getting a new ticket on re-entry. You get to pass through Gary, Indiana, which has a great song, but is otherwise a bleeping bleephole the likes of which you have never before imagined. I've had road construction divert me onto scary-looking Chicago-area streets with no further instructions or “detour” signs telling me what to do next.
Eventually you get to Iowa, where things aren't so bad, but by that point your spirit is broken. I'm not kidding: never go this way. Trust me. The relative pleasantness of Iowa and Nebraska doesn't make up for what you just went through – or what is in store: I-76 through the Colorado prairie is even less interesting than it sounds. The I-80 Northern Route has its uses, and its good parts, but this cross-country drive is not among them.
In 1985 I attended motorcycle school in Arizona. I rode my bike from Brooklyn to Phoeniz, AZ, and took the route on the first map.
Posted by: Kofla Olivieri | 22 September 2010 at 02:09 AM
That was the first route I took, too, and I'm glad it was, because it's the best one, and it led to my love of long-distance road trips. Nothing's better.
Posted by: Jeremy | 22 September 2010 at 02:43 AM
I've driven the Iowa to New England route on 80 many many times all year. Thankfully not lately and never again. I drove across country a few times too. Sadly, on the bad route. But I really enjoyed the West starting in the Rocky Mountains until the suburbs of Vegas.
Some thoughts on states on the Bad and other routes -
New Jersey and eastern megalopolis states: insane drivers abound once you come down hill
Ohio: at least the rest stops are nice. Bigger than you expect.
Pennsylvania: the longest and most boring Eastern state. Hicks galore.
Indiana: thankfully short
Illinois: Chicagoland is misery but once you are out of that, just boring.
Eastern Iowa: same as all the rest you have just driven but much more corn and soybeans.
Western Iowa: starts to feel more Western
Nebraska also changes at the mid point. Suddenly, you are in the classic West landscape of the Platte.
Colorado also changes from boring rangeland to mountain splendor then it too changes to a kind of high desert.
Utah really does have nothing but great scenery. Plan your stops there in advance as you are right about no gas, etc.
The time in Nevada is so short it really left little impression except: what a dumb place to build a city!
Southern California is desert then suburban sprawl catastrophe and traffic until you head north.
Although I have not driven it, I would agree that the southern route looks really great.
Posted by: JC | 14 November 2010 at 11:41 AM
We've been planning to drive the length of Route 66 but we've been told these days it's hard to follow. Do you have any tips for someone who wants to drive it?
Posted by: Loucindy | 13 May 2011 at 01:50 PM
It is very difficult to follow now. You need guidance. There are books and maps you can buy (look on Amazon, there are quite a few), and there is this wonderful website: http://www.legendsofamerica.com/66-main.html
Without guidance you will miss a lot. There are stretches of Old 66 that you really have to look for nowadays. (And there are stretches where you will risk damaging your tires, and/or getting lost, if you don't know what you're getting yourself into.)
Posted by: Jeremy | 13 May 2011 at 05:35 PM