What's new: Enhancements and fixes
Three ways to support Gmap4
1. Visit my other site PropertyLineMaps.com and find out how to obtain an online map link showing your property boundaries and a GPX file with the coordinates for the property corners. I developed software that uses a unique approach to efficiently produce GPS corner coordinates for property with a goal of being within 30 feet of accurate on average.
Income from this site helps to fund further development of Gmap4.
2. Of course you can always make a donation.
3. Post a link to a Gmap4 map in a forum somewhere. There are always current threads in all kinds of forums that are discussing a specific location and which would benefit greatly if someone (like you) posted a map link so people reading the thread could see the place being discussed.
The updated Gmap4 Help page has important information for using the new features described below. If you download a file from the Help page then try scanning the table of contents to find the information you want. You can also visit the Examples page to see sample maps demonstrating many of these features.
May 2, 2017 Gmap4 version 8.2
1. State Legislature Districts
You can now easily view maps showing state legislature districts with a consistent look and feel across all states. Click a district and a popup will appear with information about the person(s) elected to represent that district.
These maps are a built-in overlay that you can turn on as follows:
Open any Gmap4 map.
Click the basemap button (next to the "Menu" button).
Look under the "Overlay" heading (mobile users need to scroll down).
Click the layer "State_legislature_districts".
When you are displaying any of the state legislature maps, you can click "Map Tips" in the upper left corner for more information. Among other things, the "Tips" will show you how to make your own custom Gmap4 link to highlight any state legislature district when the map opens. The "Tips" also include links that display examples of districts that are so bizarrely shaped that they are undoubtedly gerrymandered.
Many state legislative districts are gerrymandered into grossly bizarre shapes. Both parties do this. Whether you are blue, red, black, brown, green or any shade in between, gerrymandering harms you since it allows politicians to choose their voters instead of allowing voters a fair and equal opportunity to choose their politicians.
2. All white basemap
Gmap4 links can specify the basemap that will be displayed when the map opens by including a "t" parameter in the link. If the Gmap4 link includes t=awb then the "All white basemap" be displayed when the map opens. This is one way to focus attention on a data overlay. For example, the following link displays the Ohio senate districts on the all white basemap. To change to a different basemap, click the baemap button (next to the Menu button).
For more information here is a pdf file that describes the link parameters that Gmap4 understands.
Previously a double-click only centered the map on the spot clicked. Now a double-click will both center and zoom the map in one step. This helps to make the Gmap4 interface more consistent with other map software.
February 24, 2017 Gmap4 version 8.1
Congressional District Boundaries
The congressional district boundaries have been added to the list of overlays that can be turned on with just two clicks. All you need to do is:
1. Open any Gmap4 map.
2. Click the basemap button (next to the "Menu" button).
3. Look under the "Overlay" heading (mobile users need to scroll down).
4. Click the layer "Congress_house_districts".
If the map shows solid colors then zoom in until the solid colors go away. The congressional district lines will then be very easy to see.
Click a district for a popup that includes the representative's name, party and website.
You can also use the new Gmap4 link parameter &congress= to display various congressional districts when the map opens. Here are a few examples.
Show all congressional districts
Show all congressional districts and center the map on Alabama
Show all congressional districts and highlight Alabama district 6
Show only the Ohio congressional districts
Show only the Ohio congressional districts and highlight district 4
Show only the Texas 2nd congressional district
One purpose of this map is to draw attention to gerrymandering. Pan around the map and find districts with really weird shapes. Gerrymandering allows politicians to pick their voters instead of allowing voters to pick their politicians.
To learn more about this map and additional ways you can use the new &congress= parameter, please open any of the example district maps show above and then click "Map Tips" in the upper left corner of the map.
Remember, you can make your own custom map link by making the map look the way you want it to look on your screen and then clicking Menu ==> Link to this map.
May 15, 2016 Gmap4 version 8.0
All Gmap4 links will now use https. This means that any data that flows in either direction between you and the Gmap4 server is encrypted. You will see a padlock on the browser par.
If you are making new Gmap4 links, then please start your link like so:
https://mappingsupport.com/p/gmap4.php? and then add whatever parameters you want.
There is no need to change existing Gmap4 links. Existing http links out in the wild will automatically use https when the link is opened.
This change affects all links for the MappingSupport.com domain.
Gmap4 can still display data from web sites that can only be reached by http. However that data will not be encrypted as it travels through the internet.
You might notice a few places on the Gmap4 website that have links to other web sites that begin with http. I checked each of those websites and at the time I did so those sites had not implemented https. Gmap4 shows you those http links but does not make them clickable. Browsers generally do not like it when a https web page includes clickable http links.
If you run a website yourself and are considering changing to https, then I encourage you to check out the free ssl certificates from https://letsencrypt.org/.
2. More detailed USNG and MGRS grids
If you have turned on a USNG grid or MGRS grid, then you can now display a 10 meter grid. You will need to be looking at an aerial basemap and also zoom in before the grid goes to 10 meters.
January 1, 2016 Gmap4 version 7.1
1. New basemap - USA aerials hosted by USGS < === Best new feature
The basemap menu now includes a choice for "usgs - Aerial USA partial"
These high resolution aerials cover a lot - but not all - of the USA. The aerials were obtained by various government bodies from the local to national level and copies provided to the U.S. Geological Survey which is hosting the data. In many places these aerials were taken when there were no leaves on the trees so it is possible to see features on the ground that you cannot see on the Google aerials which are generally taken with leaves present.
If you turn on this new basemap and do not see anything, then there might not be coverage in your area. Try zooming out until some images appear.
Start Gmap4 and display the new basemap:
usgs - Aerial USA partial
2. Mobile users can rightclick the map
Tap '>' at the left edge of the screen
Drag the crosshair that appears
Tap the crosshair and the rightclick popup appears
If this crosshair is not on the screen, then tap '<' to close this feature and then open it again.
3. Rightclick popup
The rightclick popup now includes a "Link to this spot" button which will generate a Gmap4 link with the map centered at the spot that you clicked.
Also, if the rightclick popup causes the map to move then when the rightclick popup is closed the map is restored to its original position.
4. Driving directions
This feature is working again after being broken for awhile.
There are two ways to access this feature.
First, you can rightclick the map and then click one of the buttons at the bottom of the popup.
Second, mobile users can turn on geolocation (Menu ==> My location) then tap the location symbol then tap the directions button. The start of the trip will be your current location.
One end of your trip is filled in with coordinates using the current coordinate format. The other end of your trip can be an address, placename, USNG coordinates or any other coordinate format that Gmap4 understands.
The blue line that appears on the map is draggable and the turn-by-turn directions will update accordingly.
If you get directions with a cell phone or tablet and also turn on geolocation then the symbol showing your location will follow the blue line on the map as you drive that route.
5. More GIS data
In addition to user-specified ArcGIS MapServer layers, Gmap4 can now also display user-specified ArcGIS ImageServer data. For example, below is a link that displays relatively high resolution aerial photography for a lot (but not all) of the U.S.
This ImageServer data is hosted by the U.S. Geological Survey and comes from a variety of sources. More data is always being added. One nice thing about this data is that a lot of these aerials were taken when there were not leaves on the trees and therefore you can see features on the ground such as small 2-track roads, ATV trails and rock walls. Those features are typically not visible on the Google aerials which are usually taken when the leaves are on the trees.
For the Gmap4 syntax to display ArcGIS ImageServer data please see:
6. New look to map controls on desktops and laptops
These changes are coming from Google, not me.
The zoom control in the upper left corner of the screen is now a large "+" and "-" instead of the sliding control. You can still use a mouse wheel to zoom (unless you are looking at an embedded map).
Also the 4-way panning control is gone.
7. Google Earth interface is gone
This has been disabled by Google due to security concerns.
Hopefully Google can figure out a safe way to implement a replacement.
8. Google streetview
This feature is only available if the basemap is:
m - Street Map Google
s - Aerial Google Satellite
h - Aerial Google Hybrid
t1 - Topo Google Terrain
This change is necessary to comply with Google's terms of service
9. Changes to Google aerial tilt
If you display the Google aerial and zoom in far enough on many urban and suburban areas, then the aerial photo tilts so instead of looking more-or-less straight down, you are looking at an angle. That tilt feature has been disabled when any of the following are true:
The My location feature is on
The map is displaying GIS data
The map is displaying a USNG, MGRS or UTM grid
Allowing the Google aerial to tilt makes the above features not work correctly therefore tilting of the Google aerial has been disabled when any of the above features are being used.
10. Fixed various minor things
If something looks like it is not working right, please email me.
11. Tip - Firefox
If Gmap4 is slow or seems to freeze, then the reason might be due to Firefox not correctly reusing space in its cache. There are two things you can do.
First, make sure you are using the latest version of Firefox.
Second, clear the Firefox cache by doing:
Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"
12. Tip - Mobile users
If Gmap4 is not working or acting weird on a cell phone, tablet or other mobile device, then you might not have enough free memory. Try closing all other open apps and then restarting Gmap4. And keep in mind that your mobile device has to be online in order for Gmap4 to start.
Yes, Gmap4 finally has a Facebook page. I will be posting tips there along with any important information affecting the status of Gmap4. If you are a Facebook user, then please stop by and give it a "like".
February 3, 2015 Gmap4 version 7.0
1. Display GIS attribute data < === Best new feature
A prior update added the ability to display symbols for data that was stored on GIS (Geographical Information System) servers. You can now click on those symbols and see the information (i.e. attributes) that are stored on the GIS server for the thing that you clicked.
GIS attribute data can be extremely useful! It is not unusual to see one or more attribute values that are links which lead to further information about the thing that you clicked. Below is an example.
A few GIS layers do not presently display attribute data. It depends on how the GIS server is configured. Additional coding is underway for those layers.
Note: When a map includes GIS overlay layers then you cannot doubleclick the map to re-center it. The doubleclick feature is disabled so it does not conflict with doing a single click to display GIS attribute data.
Note: When the popup is displaying GIS attributes or a message, then you cannot click the map below the popup. Clicks below the popup will be ignored. Either drag the map so the area you want to click is to the right of the popup area, or close the popup and then click the map.
The following map accesses a GIS server run by the U.S. Forest Service and displays symbols showing recreation opportunities. The map opens zoomed in on a spot in the Mt Baker-Snoqualmie National Forest east of Seattle but you can shift the map to any national forest in the USA.
Click the red symbol near the center of the map.
A popup will appear (might take a few seconds) and display all the attribute data stored on the GIS server for the feature that you clicked.
Look in the 'Name' column of the popup, find RECAREAURL and then click that link.
You will see a detail page that the USFS maintains for the recreation feature that you clicked.
This map can display recreation opportunities and their attribute values for all USA national forests!
(((If you do not see a red symbol at the center of this map it means that the forest service GIS server is temporarily offline or painfully slow. Please try later. Meanwhile you can visit the next link and look at various recreation related maps that can display GIS data including attribute values.)))
To see a variety of maps that can display many recreation-related GIS layers you can visit
Each of these Gmap4 maps has a number of GIS layers that you can turn on/off and click on to display the GIS attribute data that is available.
2. New 'Help' information for displaying GIS symbols and attributes
A new 'Help' page shows you how to locate data on a GIS server that Gmap4 can display and how to build a Gmap4 link to display that data. If you want to have a good understanding of Gmap4's ability to display GIS data, including attribute values, then you will want to look at this help page.
3. Gmap4 startup
You can make a Gmap4 link that will have the search feature turned on when the map opens.
4. Link to replicate the map on your screen
"Link to this map" now correctly includes the parameters for tilt and crosshair if these settings have been changed from their default values. Note that tilt will be OFF if the Gmap4 link says to display a UTM/USNG/MGRS grid.
5. Mobile and zoom level
Maps on cell phones or other mobile devices always display the zoom level in the upper right corner. This is to help when you want to use Gmap4 offline. See the "offline" pdf file on the Gmap4 Help page.
Since information about features added many months ago is not very useful, that information has been removed from this page.
11-26-2009 Gmap4 version 1.0 Initial release