Zip code by addresses

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.

When this happens, the Census Bureau will assign the entire block to a single ZCTA in this case, because the census block is the area that is precisely measured. If you are getting very precise usually a matter of meters, not miles , census block boundaries near the edge of a ZIP code almost always split ZIP codes. The statistics provided by the Census Bureau can give insight into the demographics within the ZIP code. For instance, see our ZIP code rankings. Remember that ZIP codes were made to make mail delivery easier.

That means that any given post office is only servicing what it can reach in a day. ZIP Codes reflect that. Typically, a ZIP Code is tied to a post office; by that we mean, every one of the latter has one of the former. You might think of ZIP Codes as a mailing address for a particular post office. Some do handle more than one ZIP Code, but a one-on-one game plan is the norm.

It's very important to note that ZIP Codes aren't "boundaries. They don't follow geographic or administrative boundary lines; they can cross city, county, or even state lines.

They follow where the delivery trucks go. Some ZIP Codes are special cases. Among them are "military" ZIP Codes, which include everything from military bases domestic or otherwise to battleships at sea. Then there are "unique" codes. Businesses and organizations sometimes get their own ZIP Codes, due to the volume of mail they send and receive. These are frequently benefiting from bulk mailing discounts, since the organization usually has a mail department that 1 presorts mail before giving it to the USPS, and 2 distributes mail internally so the USPS doesn't have to.

Using full ZIP Codes ensure the fastest, most accurate mailing possible. They're only provided for an address once the address has been standardized , validated and proven real. These codes indicate a specific delivery route , meaning the actual path the mail truck would travel in a single drop-off.

Usually this comprises ten to twenty homes or locations. Because ZIP codes plus 4 extra digits are based on delivery routes instead of more permanent boundaries, the last 4 digits of a complete ZIP Code can change often. Not so for the full 9-digit ZIP Code. For another thing, they can help get you those bulk mailing discounts. Another important benefit to using the last four digits of ZIP Codes is delivery speed.

That's right, your mail can show up faster if you label things right.