Property Line Maps

At Property Line Maps we produce online maps for your cell phone or computer that show your approximate property lines on the Google aerial and on the USGS topographic map. Each client also receives a GPX file with approximate corner coordinates that can be loaded into many handheld GPS units.

If you are reading this on a cell phone or small tablet, then please visit for all the details and to place an order. But if you are reading this on a large tablet or other large screen then we recommend you visit to learn more.

After we process your order, open the email we send you and click or tap the link to open your online map on almost any device from cell phones to desktop computers. If you open your online map with a cell phone then you can turn on a geolocation feature and see where you are as you walk around your land. No cell connection on your land? No worries! We show you how to use your cell phone offline.

Or instead of using a cell phone you can load the GPX file we send you into many Garmin GPS units and find survey stakes or find approximate property lines.

Most single parcels cost $59.98 and include the online map link and GPX file.

Although the property corner coordinates and property lines we produce are approximate, they are still the most accurate coordinates you can get without hiring a surveyor. But if you need to know exactly where your property corners and lines are located, then you will need to hire a surveyor.

Property Line Maps on Facebook

Gmap4 Enhanced Google Maps

Gmap4 is an enhanced Google map viewer that is free for non-commercial use. It is used by people that enjoy a wide range of outdoor activities. Click a link and the map opens in the browser on most devices from cell phones to desktop computers.

Cell phone and other mobile users see a touch-friendly interface and can turn on geolocation.

You can view Google aerials, high resolution USGS topographic maps plus other basemaps. You can display GPX files and KML/KMZ files. You can also display user-specified GIS (Geographical Information System) data including all GIS attribute data.

One of the unique features is the ability to surf GIS data almost as easily as you surf the internet. There are many thousands of layers of data hosted on GIS (Geographical Information System) servers operated by all levels of government. Gmap4 can display that data. This is a new feature that was added in 2018.

The Gmap4 homepage has a FAQ for new users, examples, a 'Quick Start' pdf file (on the Help page) and more.

Gmap4 on Facebook

Gmap4 Special Maps

Tip: Many of the maps that I have produced include a link in the upper left corner titled "Map Tips" or "About this map". That link has information, including any legend, to help you get the most benefit from the map.

Congressional district maps
The large button you see above will open the "Map Tips" page for the congressional district map. That "Map Tips" page has links to (1) open the map and display all congressional districts, or (2) display just the districts for one state or (3) display just a single congressional district. The "Map Tips" page also describes the source for this data.

State legislature district maps
Another of the large buttons you see above will open the "Map Tips" page for the state legislature district maps. That "Map Tips" page shows how to easily open the map and display (1) state house districts for any state or (2) state senate districts for any state. You can tell the map to highlight any district when the map opens. The "Map Tips" page also describes the source for this data.

GIS Maps
A great many government agencies from the federal to local level are hosting data on public-facing GIS (Geographical Information System) servers. Gmap4 can display most of that data. Most Gmap4 GIS maps have well over a dozen data overlay layers that you turn on/off and restack. These GIS maps do not display a static file where the data never changes. Instead, each time you open one of these maps or turn on a data overlay layer, the most recent data flows from the GIS server to your screen.

If you click the "Map Tips" link in the upper left corner of a GIS map then you can quickly learn how to (1) turn other GIS overlays on/off, (2) how to display GIS attribute data for the overlay that is "on top", (3) how to make your own custom map link so the map opens the way you want it to look and more useful tips.

Here is a PDF file that lists more then 600 federal, state and local GIS servers with open data.
List of government GIS servers with open data

Aerial Photo Maps
After certain large disasters NOAA takes aerial photos that are then georeferenced and placed online. These flights might continue for several days. Usually the photos are available for viewing the day after they are taken and sometimes even the same day. To see a list of areas covered by the photos click "Map Tips" and then click "____ aerial photo index". The same Gmap4 map link will display all the aerial photos NOAA takes related to that disaster. Zoom out and drag the map to other areas or use the "Menu ==> Search" feature.


FindMeSAR ( ) is a browser app for smartphones that displays the user's coordinates and accuracy value. Within 30 seconds many users will see an accuracy value of about 5 meters (~16 1/2 feet).

The "Next Format" button will scroll through four coordinate formats. Each one has a different colored screen.

Tip: If you call or text 911 then the dispatcher might not know your location unless you tell them! Everyone with a cell phone needs a super easy way to display their coordinates and accuracy value in a stressful emergency situation. Whether you have FindMeSAR or a similar app on your phone is not important. What is important is that everyone have an app that easily and quickly displays (1) their coordinates in decimal degrees and (2) the accuracy value.

How to make FindMeSAR ready for when you need it in a hurry:
1. Open FindMeSAR
2. Tap the "Next Format" button until the yellow screen appears. This screen shows your coordinates in decimal degrees which is the format used by 911 dispatchers.
3. Save the app's icon on your home screen.

When you tap the icon to open the app, it will automatically display the yellow screen. If you provide your coordinates to 911, then also be certain to give the equally important accuracy value.

To learn more about the app and get additional tips, please open FindMeSAR and tap the About button.


Test your cell phone location accuracy
FindMePro is a browser app that anyone can use to find out which settings on their cell phone or tablet produce the most accurate latitude longitude coordinates showing their location. I produced this browser app after discovering that my iPhone 4s sometimes produces coordinates with a good accuracy value but which in reality are wrong by several miles.

While you can try FindMePro on desktop and laptop computers, typically the accuracy will be very poor. FindMePro is intended to run in browsers on cell phones and tablets.

This app lets you:
1. Ask your browser to keep giving you your location coordinates while improving the accuracy.
2. Display the details for each set of coordinates on your screen.
3. Display each location on the Google aerial. Smaller circles indicate more accurate coordinates than bigger circles.
4. Adjust certain settings that are used by the app. For example, you could ask your browser to give you just a single coordinate instead of a stream of coordinates.

Open FindMePro

Typically when you tell this app to start collecting data the first locations returned are not very accurate and result in big circles on the map. Fairly quickly the accuracy should improve until the circles have about a 5 meter radius.

About button
The app’s “About” button has more information on how you can test your cell phone to find out which settings on your phone produce the best and worst coordinate data.

Crowd sourced buttons
The two "Crowd Sourced" buttons have information on sharing your results so we all learn how to get the most accurate coordinates from our phones and how to recognize bad coordinates.

Two reasons for poor coordinate accuracy
First, certain settings on your phone can influence the accuracy of the coordinates your phone produces. Please read the text under the "About" button for suggestions on which settings you might want to test. Second, FindMePro tells your browser to only report coordinates for your current location and to *not* report any cached coordinates for any prior location. Some (all?) browsers ignore this instruction and sometimes report cached coordinates that can be wrong by several miles. For more information tap the "Crowd Sourced Results" button.

How to compare coordinates produced by other apps
1. Use FindMePro to collect coordinate data and display the map.
2. Tap Menu ==> Search
3. Enter coordinates from any other app into search bar at the top of the screen.
4. Tap Go
The map will center at the coordinate you enter. You can see how, that location compares to the green circles (last three coordinates) produced by FindMePro.

Offline use
Currently FindMePro only works if you are online. The browser technology needed to implement offline use is currently undergoing a major change (from 'appcache' to 'service workers'). After most browsers implement this new technology and it is stable, then support for offline use will be added to FindMePro.

Calling 911 With a Cell Phone
Tips That Might Save Your Life

Big picture most important take home point The 911 system does not make any use of the coordinates produced by your cell phone. Instead, the 911 system uses coordinates that are intentionally dumbed down and less accurate than the coordinates produced by your phone. In short, Uber uses more accurate coordinates to give you a ride than 911 uses to try and save your life.

These tips for calling 911 with a cell phone were developed in part after an extensive review of documents on the FCC website. In addition, input was received by people working in the telcom industry.

Among other things you will learn why it is important to try calling 911 even if your phone says 'no service' and why everyone needs an app on their phone that will display their coordinates and the equally important accuracy value.

Cascadia Rising and USNG

Cascadia Rising assumes a 9.0 earthquake takes place just off the Washington, Oregon and northern California coast. In June 2016 many government agencies at all levels conducted an exercise on responding to such a mega disaster.

U.S. National Grid (USNG) is the coordinate system adopted by FEMA and other federal agencies as a standard that they will use during a disaster response.

Chaos over location of people, places and events is what you get after a disaster when responders from near and far are not all using the same coordinate system and therefore *not* speaking a common "language of location". Although they likely know better, the state and local agencies failed to agree that they would all use the USNG coordinate system during the exercise.