All mail with the same first 3 digits is first delivered to the same sec center where it is sorted according to the last 2 digits and distributed to local post offices. 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.
Add points, lines and shapes to any map, and save Drawings to your My Account page! Add multiple drawings to any of your maps! Also, measures and displays length and area automatically when you draw or edit any of your lines and shapes!
Define a delivery area, service area or sales territory using a list of 5-digit or 3-digit U. ZIP Codes. Create a custom color-coded map using a live link to a Google Sheet containing U. Share your spreadsheet using these steps: 1 Click the Share button in the upper right corner, 2 click the Get link section in the box that appears, 3 change the sharing setting to Anyone with the link keep the drop-down to the right set as Viewer , 4 click the Copy link button, and 5 click Done.
Paste the link you just copied into the box below:. Add points to the map from a live-linked spreadsheet! Set a title for your map, set the main color and choose other map layers to display all optional. Set color. Map type. Center map on user location. Show county lines. Show city limits. Show labels. Show ZIP Code boundaries.
Also show these outside my custom area. Click Apply to view your finished map. If desired, add additional mapBuilder modules to your map and make any other adjustments, then click Apply to see the updated map. When you are happy with your map, you can:. Link copied to clipboard! Save the finished map to your My Account page:. Map saved! Quickly check what ZIP Code an address is in with this free tool.
Google zip codes anywhere in the US. For example, type Help improve this tool. Please comment. Enjoy an ad-free experience across this entire website!
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