Where 'speeding' is legal: A map of maximum limits across the U.S.

[cpzilliacus]

Washington Post: Where "˜speeding' is legal: A map of maximum limits across the U.S.

The Great Plains, with all that flat, wide-open and sparsely populated land, has long had the most generous – or audacious – speed limits in the country. Cross the Minnesota border into South Dakota, and the default statewide speed limit on the interstates there, as of this spring, is now 80 miles an hour.

Idaho, Wyoming and Utah have also pushed their legal limits that far. Texas, meanwhile, has a toll road that tops out at 85. Which, as we all know, means there are drivers there traveling 90. The Missouri River, as it turns out, is a kind of speed-limit fault line: Most states west of it consider legal what Virginia, Ohio and Illinois would call "speeding."

The above map, from MetricMaps, illustrates that abrupt division using local speed limit data collected by Navteq (which powers a lot of in-car navigation tools) and provided by the mapping platform Caliper. That map shows the maximum local speed limit for any local roads or highways in each Census block group in the U.S. (that's a unit of geography smaller than many neighborhoods). If a highway passes by your house, in other words, your neighborhood may look dark blue.

[pianocello]

So they're making news out of the difference of speed limits on different roads? It's pretty obvious that freeways will have higher speed limits than surface streets, so the map zoomed in looks basically like a freeway map of any given city.

Incidentally, according to the map, the Missouri River doesn't look like any kind of "fault line"; for almost the entire length of the river, the speed limit is the same on both sides.

[pctech]

There is dark side to higher speed limits. Increases fuel consumption, pollution and potential for nastier accidents.
75 is the highest in Louisiana, on some isolated sections of I-49

[1995hoo]

There is dark side to higher speed limits. Increases fuel consumption, pollution and potential for nastier accidents.
75 is the highest in Louisiana, on some isolated sections of I-49

Of course, there's nothing requiring anyone to drive at the higher speed limit (as long as you stay to the right except if you have to move over for a left-side exit). If you don't like going 75 mph, you're perfectly entitled to do 70.

I think the Texas DOT's position when they started posting 80-mph speed limits was eminently reasonable. Some media member trotted out the standard comment about fuel consumption and the Texas DOT spokesman said, more or less (I don't recall the exact wording), "If drivers want to spend more money on fuel by driving faster, that's their decision."

[jeffandnicole]

The Missouri River, as it turns out, is a kind of speed-limit fault line: Most states west of it consider legal what Virginia, Ohio and Illinois would call "speeding."

I really don't get this sentence.  Generally speaking, the speed limit that is legal on an interstate highway would be considered illegal on the roadway I'm using when exit the highway. 

So what if a speed in one area is considered illegal in another area?

It's a slightly interesting map, but sounds like the author had to try really, really hard to justify a story here.  It seems more like product placement, with MetricMaps being the clearest thing in that whole graphic...and appears in 3 different forms (@ handle, website, direct link).

[Brandon]

There is dark side to higher speed limits. Increases fuel consumption, pollution and potential for nastier accidents.
75 is the highest in Louisiana, on some isolated sections of I-49

Riiiiight.  Your worst fuel consumption and pollution for that matter) is at 0 mph.  Your worst accidents occur at intersections in urban areas.  All higher limits do is to a) reflect how people are really driving freeways, and b) bring the lower speed group up in line with everyone else.

[slorydn1]

There is dark side to higher speed limits. Increases fuel consumption, pollution and potential for nastier accidents.
75 is the highest in Louisiana, on some isolated sections of I-49

Riiiiight.  Your worst fuel consumption and pollution for that matter) is at 0 mph.  Your worst accidents occur at intersections in urban areas.  All higher limits do is to a) reflect how people are really driving freeways, and b) bring the lower speed group up in line with everyone else.

+1

I agree wholeheartedly with Brandon.

[peterj920]

They forgot to shade Wisconsin's interstates at 70 since that is now the max speed limit as of June.  As for the fuel consumption, I get about 8 mpg better driving 75 on a freeway than I do driving in the city.  The best way to limit fuel consumption is to keep traffic flowing in urban areas.

[jeffandnicole]

They forgot to shade Wisconsin's interstates at 70 since that is now the max speed limit as of June. 

The data was collected prior to June.  I forget if they actually mentioned the date used as reference.  They did mention NYC's new 25 mph speed limit was put into effect after the data was collected as well.

[vtk]

Incidentally, according to the map, the Missouri River doesn't look like any kind of "fault line"; for almost the entire length of the river, the speed limit is the same on both sides.

I think some people believe the Missouri River forms the western border of that column of states bounded on the east by the Mississippi River.

[PHLBOS]

There is dark side to higher speed limits. Increases fuel consumption, pollution and potential for nastier accidents.
75 is the highest in Louisiana, on some isolated sections of I-49

Riiiiight.  Your worst fuel consumption and pollution for that matter) is at 0 mph.  Your worst accidents occur at intersections in urban areas.  All higher limits do is to a) reflect how people are really driving freeways, and b) bring the lower speed group up in line with everyone else.

+1

I agree wholeheartedly with Brandon.

Not to mention that multi-speed and overdrive transmissions have helped blunt the fuel consumption factor quite a bit.  When the NSL came into being; most transmissions offered on vehicles were either 3-speed automatics and 4-speed (and some 5-speed) manuals.  Today, most automatics are at least 4 or 5 speed with the highest gear being an overdrive gear.  Chrysler even offers an 8-speed automatic on many of its models.

Simply put: the more available gears on a transmission, the less revving (RPMs) at higher speeds (when set on those gears); the less revving, the lower the fuel consumption.

Real-world examples:

1.  My 2007 Mustang V6 with the 5-speed automatic gets its best average fuel economy at an average speed of 72 mph.

2.  On two different occasions, my brother rented Crown Victorias (one a '94, the other a 2002 model) with the standard single-exhaust (non-HPP nor Police Package) and obtained an average of 27-28 mpg (well above the stickered highway estimates) while averaging 70-75 mph.

Long story short; driving 55 mph with most if not all of today's vehicles (vs. say a '73 Chevy Nova) doesn't necessarily save fuel anymore vs. driving at higher speeds.

[SP Cook]

"55 saves gas" is just as much of a debunked myth as "55 saves lives".   

The WaPo is, yes, actually making news of the fact that speed limits vary.  Wow.

A better article would be for it to say "for two decades, we, from our urban perch, pontificated upon the NMSL, which we supported fully, thinking we knew better how to run roads we had absolutly no actual knowledge of, the NMSL has, over our objections, finally been repealed and, fuel mileage is WAY up and traffic mortality and morbidity are WAY down, we did not know what we were talking about and will consider our previous idiocy when purporting to opine on future subjects."

[1995hoo]

I'm sure one (not the only, just one) reason why so many people continue to spout the "slower = more fuel efficient" principle is that the proliferation of automatic transmissions and many people's inability drive manual-transmission vehicles means that if you tell people the most fuel-efficient speed is the slowest speed at which you can cruise in your highest gear without lugging the engine on uphills or needing to downshift regularly, they won't have a clue what that means.

Plus the American mindset these days tends to run to wanting bright-line rules. Telling people the most fuel-efficient speed depends on your particular car is, of course, entirely true, but it seems to be unsatisfactory for people who have become used to having other people think for them. So instead we hear things like "your car will be more efficient at 55 mph" or the like. As PHLBOS notes, that's not necessarily true. I get better fuel economy at 65 mph than I do at 55 because, with my six-speed manual, I'm revving higher in fifth gear at 55 than I am in sixth gear at 65. 60 mph feels just a tad too low for sixth gear, especially if I hit a hill or want to pass someone.

I'd say I was getting pretty darn good fuel economy in a 2004 Acura TL at this point (no doubt I'd have gotten even better fuel economy at 65 mph, but I also would have annoyed everyone else on I-95 by driving too slowly)....




Going back to the Washington Post article, I continue to find it ludicrous how some East Coast commentators cannot seem to fathom that western states allow higher speed limits on roads other than Interstates. I think most rational people, other than the Joan Claybrooks and Hillary Clintons of the world who want a return to the universal 55-mph speed limit, have absolutely no problem whatsoever with states setting higher speed limits on Interstates and with recognizing that conditions vary wildly between states in terms of terrain, traffic, weather, overall road design, etc. But I do not understand why so many people cannot seem to understand that the exact same principle applies to non-Interstates!!!!

Put differently, the following question irks me:

But this national map also raises a question central to "vision zero" campaigns trying to end pedestrian deaths and make roads safer: Does it make sense that a residential neighborhood in Houston would allow faster traffic than a residential neighborhood in Brooklyn?

Now, I have never been to Houston (or, if I have, I was one year old and so don't remember), and I therefore have no idea what the residential neighborhoods there look like. My grandparents lived in Brooklyn, however, and I've visited there many times. The streets are often pretty narrow, with parallel parking on both sides and very few driveways, most of them are busy, and you have complications like alternate-side parking (sometimes accompanied by an unwritten neighborhood toleration of double-parking on alternate-side days) that may not be common elsewhere in the country. Why shouldn't another city that might have wider streets with off-street parking possibly allow higher speed limits?

The inverse of this is that I think it's reasonable to question why East Coast states that post 55-mph speed limits on wide urban or suburban Interstates for "safety" reasons will post that same speed limit on a two-lane road with passing zones and limited visibility. I'm thinking of I-66 in Virginia from Fair Oaks (Exit 57, US-50) west to Centreville compared to a two-lane road like VA-20 from Wilderness to Orange. You cannot convince me that those two segments both share the same maximum safe speed. Yet the people who question different states setting different speed limits never want to question this sort of thing.

[jemacedo9]

Up here in Western NY, my 2013 Subaru Legacy (AWD, automatic trans) gets close to 34-35MPG when I am on two-lane roads doing 55-65MPH, but only 31-32MPG when I am on interstates doing 70-75MPH...I've monitored this lately on a few 300+ mile road trips.  Not a major enough difference for me to worry about...