Zip codes with 4

May 1 More and more companies are requiring it on paperwork and forms. We are a licensed distributor of the U. Our databases contain every street and address range in the U. Enter a ZIP Code to see all information regarding it. They also released the ZIP Code jingle:. As the US population has increased and scattered since , it's been necessary to expand on the system, to make room for everybody and their dog.

That's where the "plus 4" part comes in. We're getting ahead of ourselves, though, so let's start with the basics. If you're mailing a letter from Boston to Seattle, the mail carrier in Massachusetts doesn't really care what the street address of the destination is. It's what you might call "outside his jurisdiction. A postal worker can only cover so much ground on a given day.

And since the USPS has a standard of delivering in rain, sleet or snow, that rules out the possibility of doing the service of delivering in stages some today, some tomorrow.

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.

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.