Many of these prefixes included few, if any, subscribers. For decades, new area codes were created through a "split" of an existing area code into multiple regions. Normally, the more populated region would continue to use the existing area code.
The less populated areas would have all existing phone numbers reassigned to use a new area code to free up more numbers in the original area code. This process forced many into a new phone number which would require updates to letterhead, business cards, phone directories, personal contact lists, etc.
Many people would dial the incorrect area code which caused confusion. In , area code was created as the first "overlay" area code. With an overlay area code, the overlay serves the same geographic as the original to increase the pool of numbers available in the area. When the original phone systems were put in place, 7-digit dialing without the area code could be used to make local calls, and digit dialing with the area code only needed to be used for long distance calls.
In , area code was introduced as the first overlay with forced 10 digit dialing for local calls. Initially, there was substantial public resistance to overlays because of the digit dialing requirement for local calls. However, the last area code split in Canada was in with the split of splitting off and the last area code split in the US was in with splitting off No area code splits are currently proposed and both countries have agreed: without exceptional circumstances, all new area codes will be overlays.
Today, 7-digit dialing is broken in most major cities. Many areas not served by an overlay can still use 7-digit dialing. Something besides allocating more area codes needed to be done to improve the system. After a few trials, mandatory number pooling was implemented in with a national rollout to the largest metropolitan areas. With number pooling, an entire prefix of 10, numbers is allocated to a specific area, but phone numbers are only allocated to a specific carrier in 1, block increments.
While several US markets are still not required to implement number pooling and Canada has no number pooling, the effects dramatically slowed the need to allocate new prefixes and new area codes because of increased utilization. The rate of issuing new area codes dropped to nearly half that of the s. While it may seem that all consumers in the US use a mobile phone, more than two-thirds of prefixes are allocated for landline use. That number has been dropping by about 3.
Not all area codes are assigned to a specific geographic area. One of the most common are toll-free area codes where the caller is not billed for long distance though wireless customers may have minutes deducted from their plan : , , , , , , and The area code is also currently used for premium services that are billed to the caller at higher than normal long distance rates.
In the s and and early s, numbers were frequently used to target children to run up phone bills, psychic hotlines, adult entertainment, computer help, etc. Legislative protections in the s and the withdrawal of phone companies from passing these fees onto customers has largely killed the number industry.
Other caller-pays area codes include , , , , , , , , and Though they see much less usage now, some are still used for dial-up modem access or security systems. Area codes and are reserved for special telecommunications services and receive little usage. For looking up information on a specific phone number, the free reverse phone lookup allows you to see the name and address of phone numbers listed in the white pages of phone books throughout the US. For unlisted or cell phone numbers, we provide a convenient price comparison of popular services that allow you to search deeper for the owner of a phone number.
If you are looking for the area code for a particular city, you can search area codes by city using our area code finder. To browse all area codes, we have a list of all United States area codes by state and area codes by number. The area code list includes a printable copy that you can print and use for reference. For international numbers, we also include Canadian area codes.
For dialing internationally, see the list of international dialing codes with instructions on how to dial foreign numbers or dial U. Toggle navigation. Instant Phone Lookup Search Enter a phone number, area code, or city and state. Featured In. US Area Code Map. Canada Area Code Map. Click to Enlarge. Splits and Overlays by Year. The sec centers are not open to the public and usually do most sorting overnight.
As you can see from the map of the first 3 digits of zip codes , the digits after the first are also generally assigned from east to west. In the map, 0 is closer to white and 9 is much more vivid. It's easy to follow the gradient across each of the zones even though there are a few exceptions such as the southwest tip of Georgia which uses 39XXX like central Mississippi.
Despite the fact that ZIP codes seem to be geographic in nature, that wasn't their intended purpose. They are intended to group mail to allow the USPS to deliver mail more efficiently. Some ZIP codes will span multiple states in order to make mail routing and delivery more efficient. In most cases, addresses in close proximity to each other are grouped in the same ZIP code which gives the appearance that ZIP codes are defined by a clear geographic boundary.
However, some ZIP codes have nothing to do with geogaphic areas. When ZIP codes appear to be geographically grouped, a clear shape cannot always be drawn around the ZIP code because ZIP codes are only assigned to a point of delivery and not the spaces between delivery points.
In areas without a regular postal route or no mail delivery, ZIP codes may not be defined or have unclear boundaries. The main issue is discussed above: there simply isn't always a clear geographic boundary for a ZIP code. The Census Bureau and many other commercial services will try to interpolate the data to create polygons shapes using straight lines to represent the approximate area covered by a ZIP code, but none of these maps are official or entirely accurate.
They provide a very close approximation of the area covered by a ZIP code. You can easily notice some of the boundary issues when viewing our maps. Very rural areas aren't labeled as belonging to a ZIP code such as much of Nevada and Utah where there are few, if any, addresses to deliver mail. If the address is on the same street as a ZIP code boundary on the map, be sure to search for the full street address to determine the ZIP code instead of relying on the map.
Their purpose is to convey statistical data about regions that are familiar to most citizens. As discussed above, it is difficult to precisely define a geographic area covered by a ZIP code. ZCTAs were developed to account for some of the difficulties in assigning an area to a ZIP code and to precisely define a geographic area.
In general, they are updated once every 10 years for the Census. The Census assigns an area to a ZCTA according to census blocks the smallest geographic unit used by the census. Imagine a city block that makes up a typical census block as pictured to the right. It is bounded on all 4 sides by portions of city streets that each have their own name and addresses. The issue is that census blocks almost always split down the middle of the street. ZIP codes rarely do because that would require two postal workers delivering mail to that street - one for each side of the street.
In the example, one mail carrier may deliver to 3 sides of the block via one ZIP code while another mail carrier delivers mail on the other street in a different ZIP code.
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