60 years of North American area codes

Note:  Everything beyond about the first paragraph of the post below is strictly for those geeky enough to be interested in telephone numbering history.  You know who you are!   For everyone else, you have been warned!  

It was way back in October 1947 that AT&T finalized plans to divide North America into Numbering Plan Areas (NPAs), each represented by its own unique three-digit code for long-distance dialing.

In this initial allocation of the codes which would become so familiar to telephone users in later years, just 86 area codes were allocated, 77 for the United States plus 9 for Canada. 

In some parts of the continent, especially the western states, it would have been quite possible for one NPA to cover more than one state (or at least parts of more than one state).   It was decided, however, that state boundaries should also form the primary boundaries of area codes to make the system as easy as possible to use.   States which had a sufficient number of telephones to warrant it would then be subdivided into two or more areas.   

For reasons which would take another post to explain (if anyone is really that interested!), area codes would have to have a first digit of 2 through 9, and a second digit which was always 0 or 1.   Additionally, the codes 211, 311, 411, and so on were not available since these were already in use in many places for information, repair, and similar local services.

Click here for map of original United States area codes, 1947

Many of these original area codes will be familiar to modern telephone users, although in a lot of cases they now serve a much smaller area!    Back in 1947, only 14 of the 48 states were allocated multiple area codes, and only one - New York - had as many as five.   Alaska and Hawaii, still a few years away from gaining statehood, were not included in the plan.  Some of the allocations show just how much the population of the U.S. has shifted in the last six decades.  Who today could imagine the whole of Florida being covered by just a single area code, or a mere three area codes for California?   

So, were the area codes just picked at random and thrown onto the map, as it may appear at first glance?   Not quite.  Although assignments were arbitrary to a certain degree, they were not completely random.   First, the codes were divided into two groups: States to be served by just a single code got area codes with a "0" middle digit; states to be served by multiple codes got those with "1" as a middle digit.   Hence Georgia 404,  Wyoming 307,  Kansas 316/913, Michigan 313/517/616, and so on.

Within each of these two broad groups, allocations were then made roughly on the basis that the areas most called from elsewhere should have codes which were the quickest to dial.  Remember that this was before the era of Touchtone dialing, and rotary dialing an 8 or 9 takes quite a bit longer than rotary dialing a 2 or 3.   So, looking at the multiple-code states, that's why New York City got the "shortest" possible code 212, while other frequently called regions also received "low" codes, e.g. 312 for Chicago, 313 for Detroit, 412 for Pittsburgh.  Lesser-called places were given the "higher" codes, e.g. 715 for northern Wisconsin, 915 for western Texas.    Of course, it's not simply a case of treating these as large or small numbers, because in terms of the length of time taken to dial them, 315 and 513 are equivalent.  Similarly, 317 and 218 were considered to be of equal status, and would also be equivalent to 713, 812, 416, 614, and 515, since these all add up to the same number of dial pulses. 

Not shown on the map above, but on the Canadian side of the border two provinces had two area codes each: Ontario 416/613 and Quebec 418/514.  The western provinces were single codes:  Manitoba 204, Saskatchewan 306, Alberta 403, British Columbia 604.   Nova Scotia, Prince Edward Island, and New Brunswick all shared the single area code 902.

Although area codes came into use in 1947, only operators were able to use them at this time.   It wasn't until 1951 that any customers could dial them, when subscribers in Englewood, N.J. became the first to be able to dial their own long-distance calls in AT&T's DDD (Direct Distance Dialing) trials.   Even then, they could dial only a few selected cities in the U.S., not every area code.  That did include San Francisco and Oakland though, no doubt a deliberate inclusion in the trials as it represented coast-to-coast calling. 

It wasn't until the late 1950s/early 1960s that DDD using area codes started to be adopted more widely.  By this time though, a good many area codes had already been added to the original plan.  In fact the first ever area code "split" occurred before the Englewood trials, when 219 was assigned to northern Indiana in 1949.  These early years of the numbering plan saw many additions and changes to boundaries as the system was "fine tuned" to allow for the boom years of the 1950s and, it seems, to make certain call-routing operations easier (don't worry, I won't go into that!).   Quite a number of states which had started with a single area code in the 1947 plan were split into two areas, and other area codes were added to existing multiple-code states. 

The original distinction between "0" and "1" area codes was lost after just a few years, as both forms were added to both single and multiple NPA states.  Of course it was still true to say that a state with one code would have a "0" middle digit, but the converse was no longer necessarily true.

By the end of the 1950s, more than two dozen area codes had been added to the original plan, with Alaska 907 and Hawaii 808 now being included, plus the Caribbean area code 809.   These early changes were all in place before most people could dial long-distance at all, and thus attracted little if any public attention in most cases.

After these rapid changes of the first few years, the map settled down into a stable period.  There were some minor boundary alterations, but during the entire two decades of the 1960s/70s, only three new area codes were added on the U.S. side of the border (Michigan 906 in 1961, Florida 904 in 1965, and Virginia 804 in 1973).   The mid-1960s also saw the introduction of 800 numbers.

It wasn't until until the 1980s that demand for numbers started more frequent assignments of new area codes again, and the 1990s that all the 0/1 area codes were exhausted and a new numbering scheme implemented in which area codes could have some other middle digit.

I'm a geek and I really enjoyed that article!!

The area code where my mother lives has changed 3 times in the past 20 years, because of demand for phone numbers.  And certain areas have gone to a 10-digit dialing rather than 7. 

Has gotten a bit confusing, as during the second area code change where we lived, places across the river which had been local calls all of a sudden were "long distance"!

The area code where my mother lives has changed 3 times in the past 20 years, because of demand for phone numbers.  And certain areas have gone to a 10-digit dialing rather than 7. 

Has gotten a bit confusing, as during the second area code change where we lived, places across the river which had been local calls all of a sudden were "long distance"!

When I lived in the Twin Cities I found it a bit wierd that to call another suburb which might only be down the road we had to dial the full 10 digit number. 

Same here, peedal.  Growing up in Iowa right on the Mississippi River, we could probably see the other person's house we were calling across the river and it would be long distance.  But I suppose it's got to happen somewhere to somebody.

Interesting article Paul. Thanks for posting.

That was interesting!!

I dig geeky information like that.  Good for storing as random trivia!

Dear Post Office Paul

Very interesting. 
They never taught us the interesting stuff at school.

Thanks

Geekily yours
Telephonebob

for those wondering about Post Office Paul salutation - the GPO was the telephone company before privatisation.

Here's what the map looked like in later years, a little more recognizable to modern telephone users, but still far fewer area codes than today in some states:

Click here for U.S. area code map, 1973

Although showing the situation as of 1973, as I mentioned above only three area codes were added during the whole two decades of the 1960s/70s, so every area code on this map was in use by 1960, except for 906 (Mich., 1961), 904 (Fla., 1965), and 804 (Va., 1973).   The next addition was not until 1982 when 619 was added for California.

Canada by this time consisted of: B.C. 604, Alberta 403, Sask. 306, Manitoba 204,  Ont. 416/613/519/807/705, Quebec 514/418/819, N.B. 506,  P.E.I./N.S. 902, Newfoundland 709.   The Alberta and Quebec area codes also covered the Yukon and Northwest Territory.

And certain areas have gone to a 10-digit dialing rather than 7. 

It's only happened in more recent years (since the 1990s), and can stir up quite a bit of controversy in telecoms circles.   It's where a new area code has been implemented as an overlay rather than a split, i.e. all existing users keep their existing area code but new telephone subscribers in some or all of the area will be assigned a new area code.

Advantages claimed for overlays are that they avoid the need for all existing users to change their numbers, and that in the largest urban areas which are affected the most some area codes are already covering such small geographical areas that further splits would result in areas so tiny that almost all calls beyond a very short distance would have to be dialed as 10 digits anyway (look at how little of Los Angeles is covered by 213 today for an example). 

The counterclaims in favor of a traditional split are mostly that everybody within an area with overlays then has to dial all 10 digits for every call, and that it doesn't make a lot of sense to still call these "area" codes when you and a friend a half mile away still have the same code but your next-door neighbor might have a different code.

Some go so far as to say that overlays effectively penalize those going into the new code, since that code remains relatively unknown to many people for quite a long period of time. 

Growing up in Iowa right on the Mississippi River, we could probably see the other person's house we were calling across the river and it would be long distance.  But I suppose it's got to happen somewhere to somebody.

There are a lot of places where there is a common interest between adjoining or nearby towns which are in different area codes.  Kansas City, Mo./Kan. is an obvious example which springs to mind.

In the past, there was a trick which was often used to make things easier.   A prefix (i.e. the first three digits of your local number) which was used in one area code was reserved and not used in the other one.   Suppose you had a town which had 235 and 236 numbers in one area code (call it "A"), and 337, 338, and 359 numbers in another area code ("B") across the state line.     If you made sure that area code "A" did not have any numbers starting with 337, 338, or 359, and that area code "B" did not have a 235 or 236 prefix, then you could allow local calls across the boundary to be dialed with just seven digits since there was no conflict.  If somebody in area "A" dialed, say, 338-1234, then because there were no 338 numbers within that area, the equipment could just send the call across to the other side of town.  So you could call into a different area code without actually dialing that area code. 

In more modern times when numbers have been running short, those reserved prefixes started to become something of a nuisance, so they had to go.   As soon as your own area code has a prefix which is the same as one used "just across town" but in the next area code, you have to go to 10-digit dialing in order to distinguish between the two.

for those wondering about Post Office Paul salutation - the GPO was the telephone company before privatisation.

 

And for your bonus question:  Which is the only part of the U.K. which was not served by Post Office Telephones?

And for your bonus question:  Which is the only part of the U.K. which was not served by Post Office Telephones?

White kiosk country - Hull. The forward thinking council that had local calls for 5p for as long as they connected.

In a similar vein, for your bonus - what company had the only truly private troposcatter radio system from the offshore platforms to the UK?  This means that the UK side of the link was private and nothing to do with BT.

The 10-digit dialing now required in some areas (we got it in Baltimore back in the late 90s) can really flummox some people. I had a cousin visit from a much smaller metropolitan area and I had to leave her to go to a job interview. She was apartment hunting and had to phone to get appointments. But when I got back, she'd not been able to do anything because she had no idea you had to dial the area code even locally.

And yes, it did bugger up local/long distance charges. We ended up paying a tad extra for a phone number that allowed us to call all our family in the area at local rates.

When i lived in Denver, there were two area codes, 303 or 720.  My cell phone number was 720-xxx-xxxx.  If you dialed 303-xxx-xxxx you got some guy from the area office of the FBI. I got quite a few calls for him over the years, and I can only imagine how many times he went to his office and had voicemails of my friends drunk dialling thinking it was me.  That's actually how i found out about it in the first place; my best friend was drunk dialing and put in the wrong area code

In a similar vein, for your bonus - what company had the only truly private troposcatter radio system from the offshore platforms to the UK?  This means that the UK side of the link was private and nothing to do with BT. 

Hmm.....   I know that VHF troposcatter is used extensively for links with the oil platforms, but I think you've got me on that one.  If I were going to hazard a guess, I'd say it was either owned by one of the big oil companies itself, or contracted out and run by the likes of C&W, Pye, or Marconi.   

Hmm.....   I know that VHF troposcatter is used extensively for links with the oil platforms, but I think you've got me on that one.  If I were going to hazard a guess, I'd say either it was either owned by one of the big oil companies itself, or contracted out and run by the likes of C&W, Pye, or Marconi.   

Yep one of the big boys - BP. They got in and set up comms links and got a license from the government BEFORE BT got involved. Everyone after that had to land at a BT site. Marconi was the biggest supplier and operator for all the other 'big' boys.

For the North Sea, it was mid range of the UHF spectrum (900Mhz). Big power - 1KW+. Fairly small bandwidth. I believe they had one or two 'baby' tropos down in the southern North Sea that operated in the top end of the VHF range. To my knowledge all the tropo systems have been replaced with VSAT.

The tropo I worked on before the North Sea was in the top end of the UHF, low end of the SHF range (3Ghz). Very high for tropo. Large bandwidth (10Mhz+). Required 50KW glycol cooled kylstrons (taller than me), 120' parabolic dishes and the wave guides (YES waveguides!) that were the size of HVAC ducts ( I had never seen a waveguide larger than a few inches until then).

Like balmerhon, I lived in Maryland for many years. 301 was the local area code, which was unnecessary to use for local state calls, and 410 (which would have been balmerhon's area code) was the area code for internal state long distance calls. Then they added yet another state area code, which literally made it necessary to dial 10 digits just to talk to your neighbor across the street. It was, and is, so fricking annoying.

(Geez, that took only 20 minutes to type!)

The tropo I worked on before the North Sea was in the top end of the UHF, low end of the SHF range (3Ghz). Very high for tropo.

No kidding!    Boy, that must have been some klystron setup.  The ones we used at Goonhilly were water-cooled, and generally up to just a few kilowatts each.   The station was built for the Telstar project originally, as I mentioned over in the Sputnik thread.  That was regular satellite C-band (6GHz uplink, 4GHz downlink), which of course were the frequencies already in use for terrestrial microwave links by AT&T Long Lines et al.   We had Ku-band equipment by the 1980s as well, as you would expect.

Like balmerhon, I lived in Maryland for many years. 301 was the local area code, which was unnecessary to use for local state calls, and 410 (which would have been balmerhon's area code) was the area code for internal state long distance calls. Then they added yet another state area code

Maryland is now overlays across the whole state, so it's fully 10-digit dialing statewide.  I couldn't tell you from memory the exact date when 410 came into use, but it wasn't until the late 1980s/early 1990s.   Up until then, Maryland had only ever had its single, original 301 area code.

We can expect to see 10-digit dialing for all calls become more widespread in the years to come as more overlay area codes come into use.   The Public Utilities Commissions in some states really seem to favor overlays over splits these days. 

Ultimately, there may well come a time when all calls in the U.S. become 10 digits and the area codes are effectively absorbed into the number.   A similar change has already taken place in several European countries, such as France and Portugal.