Determine which county a zip code is in

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. Here is a simple example of how to lookup a county using a ZIP Code. We'll also look at an example of how to perform a county lookup using a mailing address.

Before you embark on your journey, there is something you need to know. Cities and ZIP Codes frequently cross county and even state lines. This means that if you enter a city or ZIP Code into our tool, it may return information for more than one county. Conversely, a single address will only ever be located in one county.

So, for the most precise results, use the full address to find county information rather than the city or ZIP Code. Step 1. Go to the website of an address validation services provider of your choice. In this example, we'll find a ZIP Code's corresponding county designation using the SmartyStreets' address validation demo. Step 2. Step 3. Step 5. When you search by an address or GPS Coordinates, the map and latitude and longitude, both the county and maps will be updated.

How to find what county am I In for my location? With the user's permission, the geolocation technology allows the browser to look up the user's current location, and the county that he lives in. How to find what county am I in for my address? As soon as you enter an address, and hit the Get County by Address, you will get the county of that address along with its latitude and longitude and a map that you can explore. You can use it on the go. As your location changes when you are driving or biking, you can refresh the page to find the new county.

Do you have an APP? If you have an Android device, you can install it for free. Currently, we do not have an app for the iPhone. What is My County App. How to get my county on my iPhone?

Just type in an address and your county will be found on your iPhone. Do you store our location information? Your County:.