New map viewer for USGS topographic maps and GPX/KML/TPO files. Free, no ads.


Hello All,

Since this is my first post here I’ll try to make it worth your while. My name is Joseph Elfelt and I’m posting to let you know about an enhanced Google map viewer I have written that (1) can open and display data from GPX files and (2) includes the 7.5ʺ USGS/USFS topographic maps.

Here’s an example using a GPX file from someone that hiked on the Pacific Crest Trail. The track in this file is for a short portion of the trail starting at the border with Mexico.

You can use this free map viewing tool to display any GPX file or KML file you find on this site or elsewhere.

The basic idea for this project was to write a map viewer that was based on Google maps and which anyone could use to display their GPS data (KML & GPX files) on interactive USGS/USFS topographic maps. Also I wanted the viewer to run full screen, have no ads and be 100% free. After I got this idea I looked to see if anyone had already produced such a map viewer and was a bit surprised when I could not find any.

Yes, there are some other map viewers that let you look at your GPS data but they were all short of what I envisioned for one or more of the following reasons:
They did not include the USGS topographic maps
They were not free
They included ads
They were limited to just part of your screen
They included GPS data from other people

This free online tool is called Gmap4 and a detailed ‘help' file is now available and can be found here:
This help file has clickable links with examples of various maps. If you look at the Quick Start section then you will be able to quickly determine if Gmap4 can be useful to you.

In order to look at GPS data with Gmap4 that data has to be online someplace. Note: In order to use Gmap4 to look at a GPX file from POI Factory you have to (1) download the file and (2) place the file online somewhere. Here’s the reason: Gmap4 cannot read GPX files straight from this site since this site does not provide a direct URL to those files. Don’t get me wrong - I’m not complaining. I’m sure the site owners have an excellent reason for setting things up this way.

Of course many people do not have their own website where they can place their GPS data online. Good news - anyone can place their GPS data online for free by making their data a “Google document”. Gmap4 can read GPS tracks, waypoints and related data from Google documents. This feature advances the state-of-the-art for Google documents and is unique to Gmap4. Step-by-step instructions are in the ‘help’ file.

But you don’t need any GPS data to use Gmap4. Below is a link to a map of the USA & Canada. Just zoom in on something that you want to see in the USA or Canada and when you find it then click the MyTopo button in order to see a detailed topographic map for that spot:,-114.7...

Finally, I’m introducing Gmap4 in a number of forums and lists related to hiking, climbing, biking, backcountry skiing, geocache, ATV, hunting, etc. While I am happy to try and answer any questions, I simply do not have time to monitor each site where I post. Here’s my suggestion. If you see a question about Gmap4 posted on this site or any other site, please send me an email with a link to the question and I will do my best to answer. And of course I would love to get an email from you if Gmap4 does not appear to be working correctly. My email address is on my contact page:

Enjoy and please feel welcome to spread the word, but I have a favor to ask of you. If you cross-post this announcement anywhere else, please drop me an email (see contact page above) and let me know where you posted. That will help me avoid making a duplicate posting on the same site.


This is Great! Thank you so

This is Great!
Thank you so much

Excellent application

MappingSupport, I also looked over your application and some of the 'help' notes. It's great! Thank you.

Winston Churchill said, “Americans can always be counted on to do the right thing, after exhausting all other possibilities.”

Thanks for the kind

Thanks for the kind words.

Here's the latest Gmap4 update.

Gmap4 can now read Google MyMaps and display that data on the USGS 7.5” topo maps. Also the on-screen interface is cleaner and the Help file has been updated.

Here’s an example of a Google MyMap I made for a hike in the Washington State Cascades:,1098344178...

Every time you make a MyMap there is a unique ‘id’ code assigned to that map. Gmap4 uses that ‘id’ code to display your MyMap. All you need to do is enter the following command into your browser. Replace the xxx.yyy with the ‘id’ code for your MyMap. Also, be careful not to let any spaces get into this command:,xxx.yyy

If you do not know the unique ‘id’ code for your MyMap then:
1. Display your MyMap
2. Click the “link” button in the upper right corner
3. Save the link and find where it says: &msid=
4. Copy your ‘id’ code. The ‘id’ code begins after the “&msid=”. If you are copying the ‘id’ code and get to a ‘&’ character, then copy everything up to (but not including) the ‘&’ character.

Finally, if you have a KML file then Google maps has a feature that lets you "import" that KML file into a MyMap. This is a very quick way to put a KML file online so you can view it on the detailed topographic maps that are available with Gmap4.

Gmap4 version 1.5.012 has

Gmap4 version 1.5.012 has just been posted. This free software adds detailed topographic maps (USA and Canada) to Google Maps and lets you view your GPS data on those maps.

Since this software runs entirely online, there is nothing to buy, nothing to download, nothing to install. When you use Gmap4 you should now see “6-26-2010 Update” in the lower left corner of your screen. If you click Actions ==> About, then it should say Version 1.5.012. If you do not see those things, then please clear your browser’s cache and try again.

This update (among other things) restores the ability to place your GPS data (KML and GPX files) online as Google Documents. This feature advances state-of-the-art for Google Documents and is unique to Gmap4.

To see the full list of what is new or changed, go to the Gmap4 homepage and click What’s New.

Updated pdf ‘Help’ file with clickable links:

Here is a sample map that includes information from three data files:,0AUba9Qv1...

Joseph Elfelt


All I get is this error or one like it:

Parse error: syntax error, unexpected T_STRING in /home1/mapping1/public_html/p/gmap4.php on line 1

Nuvi 350, 760, 1695LM, 3790LMT, 2460LMT, 3597LMTHD, DriveLuxe 50LMTHD, DriveSmart 61, Garmin Backup Camera 40 and TomTom XXL540s.

Well dang. I get the same

Well dang. I get the same error.
I also tried various test versions of the code that all worked perfectly ... up to now that is. They all throw the same error even though I've not changed any of the code.

Then I tried the old version of the production code which has worked just fine for some months. Got the same error.

I'm starting to think it's not me...
Time to call my ISP.

Please clear your browser

Please clear your browser cache and try again.
Should be working now

No Need

No need to clear my cache, it's working fine now.


Nuvi 350, 760, 1695LM, 3790LMT, 2460LMT, 3597LMTHD, DriveLuxe 50LMTHD, DriveSmart 61, Garmin Backup Camera 40 and TomTom XXL540s.

Do you have any .TPO files

Do you have any .TPO files from the National Geographic TOPO software? Gmap4 version 1.7.x can now display those files. Often the topographic maps displayed by Gmap4 (provided at no cost by will be superior and/or more current than the NG topographic maps displayed by the TOPO software.

You do need to place your TPO or other data file online before it can be displayed by Gmap4. The easiest/fastest way to place a TPO file online is via Google Sites (free). Don’t be shy. You will find hand-holding-step-by-step instructions in the Gmap4 Help file.

Here is the general recipe for building a URL to display a TPO file with Gmap4 (do not include the quotes, this is not a real link):

Below is a link to the Gmap4 homepage. Check out the 'Examples' button and Quick Start section of the 'Help' file.


Yesterday I posted version

Yesterday I posted version 1.8.1 of Gmap4. New things include:
Search (Click Menu ==> Search)
Place one icon on the map via a URL parameter (&icon=)
Print via your browser

Gmap4 homepage:
Check out the menu links for:
What’s new

Search the Help file on “(New)” to find details on the new stuff.

To the best of my knowledge the Search - List feature is unique to Gmap4.


Gmap4 has now been updated

Gmap4 has now been updated to version 1.8.2

The search feature is now much more user friendly.

Also, you can search on any reasonable way for writing latitude/longitude coordinates. This includes the geocaching format of degrees and decimal minutes.

Gmap4 homepage:

Joseph - Gmap4 author

Gmap4 has been updated to

Gmap4 has been updated to version 1.8.3

The present-day magnetic declination for the map center is now always displayed in the lower right corner. This value is produced using software from combined with data from
Since the magnetic declination is always changing, the older value printed on maps can be wrong by several degrees.

I also updated my links page to show (1) reviews of Gmap4 and (2) sites that are already using Gmap4 to produce online interactive maps.

Finally, if you are interested in the search feature and/or print feature, please check the ‘Help’ file (and use the Table of Contents) to be sure you have seen the most recent info on those features.

The link below will display a world map. To test-drive the search feature click Menu==>Search.,-16.7...

Joseph - Gmap4 author

Gmap4 has been updated to

Gmap4 has been updated to version 1.9.1 dated January 17, 2011. This version adds support for UTM coordinate grids. All UTM support in Gmap4 uses the WGS84 datum. This UTM support works worldwide. For more info on UTM coordinates see:

(Pay back time: When you visit other outdoor-related forums, please do a search and see if Gmap4 has been mentioned. If not, it would just take a moment for you to pass the word along. Also, are you doing the social network thing? Consider saying something nice about Gmap4.)

Here’s a map of Grand Canyon Village with a UTM grid.,-112....

To toggle UTM support on and off, click Menu ==> UTM On/Off. If UTM is ‘on’ then Gmap4 gives you UTM information in three ways:

1. A UTM grid is displayed. This UTM grid is displayed on both the MyTopo topographic maps (USA and Canada) and the standard views (aerial, etc) provided by Google Maps.

2. The lower right corner of the screen will always show the UTM zone and UTM coordinates for both the cursor and map center.

3. You can get the UTM zone and coordinates for any point on the map by right-clicking that point.

Things to keep in mind

You can build you own map links by using URL parameters. If you want your map to appear on the user’s screen and already have UTM turned on, then add this URL parameter: &coord=utm

Here is a comparison:
With UTM on
With UTM off (default)

If you zoom out far enough then you will not see a UTM grid. Instead you will only see vertical red lines which mark the edges of the UTM zones.

UTM grid lines that are near the edge of their zone often appear curved when displayed using the map projection used by Google Maps. The grid lines in the adjoining zone will curve in the opposite direction. For example, the next map is centered near Lake Tahoe. The red line marks the edge of adjoining UTM zones. Double click each side of the red line (this changes the map center) and watch the UTM grid lines change. The grid lines are calculated based on the UTM zone that contains the center of the map.,-120....

Some MyTopo topographic maps already have a UTM grid printed on them. Caution! Some of those printed grids are based on the older datum NAD27. Those older grids will have a uniform offset from the grid displayed by Gmap4 which is based on datum WGS84 . For example: Here is a map showing part of the Alpine Lakes Wilderness area in Washington State where the MyTopo maps have a UTM grid based on the WGS84 datum. Click Menu ==> UTM On/Off and you will see the faint UTM grid printed on the map:,-120.8...

By contrast, here is a map showing part of the Yosemite Valley area in California, where the MyTopo maps have a UTM grid based on NAD27. Note the uniform offset between the two sets of grid lines.,-119....

Usually (but not always) the different zoom levels use a different scale for the UTM grid. To learn the grid scale, compare the cursor coordinates (lower right corner) as you point to adjacent grid lines. If you want to know the zoom level, right click the map.

Maps with UTM grid lines can be printed. File ==> Print Preview

If you know of any other map viewing software that can display the MyTopo topographic maps along with a UTM grid, I would enjoy knowing about it.

Future UTM improvements

There are different methods for putting labels on the grid lines. I am pondering what will work best.
Another possible improvement is to let the user change the line width, color and/or spacing.
Other ideas?

Next Gmap4 update

Bad news: The ‘Search’ feature of Gmap4 no longer works very well for placenames. This feature uses Google’s ‘geocoding’ service on the backend. OK, I admit it. Gmap4 was pushing the envelope in its use of that service. Whoops - Google pushed back. Guess who won? I will add a second search tool that is designed to work well with placenames.

Good news: The existing ‘Search’ feature of Gmap4 still works fine for searching on (1) anything related to addresses including names of many settlements that no longer exist and (2) any reasonable way to write a latitude/longitude pair.

Finally, if you find Gmap4 to be useful I hope you can take a moment and do some ‘pay-back’ by letting other people know about it.

Joseph - Gmap4 author

Very cool and useful. Thank

Very cool and useful. Thank you!!!

Gmap4 has been updated to

Gmap4 has been updated to version 2.2. The full list of changes is posted on the Gmap4 “what's new” page (see hompage link below). Here are some highlights.

First, Gmap4 can add labels to Google maps. The labels are built from the waypoint names in your file. Your existing maps will work with this feature, except KMZ files are not yet supported. Labels can be styled with your own HTML and CSS. The following link displays a GPX file that is hosted at Topofusion and displays with labels turned on.

To open Gmap4 with labels turned on, include this parameter in your Gmap4 URL: &label=on
To toggle the labels after a map is displayed click Menu ==> Label On/Off

You can style the labels with your own HTML and CSS. This label feature works with all the file formats that Gmap4 can read except KMZ files. Label support for KMZ files will be added in a future update.

Below is an example of a map I made with fancy labels. Note that (1) each label is clickable and (2) when you shift to an aerial map view then the labels acquire a solid background so the text does not disappear in shadows on the aerials. This map uses a delimited text file that is hosted at Google Sites.

Second, a number of features have been added to the delimited text file format that Gmap4 can display. The section of the Gmap4 Help file titled “Delimited text files - Some details” has been completely re-written and now starts with a series of example maps that will let you rapidly learn the basics. If you want the most control over your map, this is the file format to use.

Third, the internet security features of Gmap4 have been enhanced. If you look at a file that causes Gmap4 to display a security-related message on your screen and you think that message is a ‘false positive’, then please go to the Gmap4 contact page and send an email. Include the URL to the map (Menu ==> Show map URL) in your email.

Fourth, Gmap4 can now display files that include a '?' character in the URL for the file.

For more information please see the Gmap4 homepage:


Joseph, the Gmap4 guy


..for the info. The UTM feature is especially useful.

The Gmap4 production code is

The Gmap4 production code is now version 2.3. This is the first version that includes special features for smartphones and other mobile devices.

1. Gmap4 can now find your location on the map. This service will use some or all of:
* Your IP address
* Cell towers
* Wi-fi hotspots
* Any GPS chip in your phone or other mobile device

Simply open any map in your phone’s browser and then select Menu ==> Findme. You can try this right now on your desktop/laptop just to see how it works. However, your desktop/laptop location will likely not be very accurate since in many cases only your IP address will be used.

You can also build Gmap4 URLs that will automatically run the Findme feature when the map opens. Simply include the parameter ‘findme=on’ in the Gmap4 URL.

Since Gmap4 uses the Google maps Application Programming Interface (API), this feature only works if your phone’s browser is online to the internet.

Also, because Gmap4 is a web application, you do not need to download or install anything in order to use Gmap4 on your phone. To open Gmap4 on your phone:
A. Open your phone’s browser. (Remember, that browser has to be online.)
B. Do a web search for Gmap4 - the first hit should be the Gmap4 homepage
C. Select the link just under the homepage title. That link opens Gmap4 and displays a map of the world.
D. Select Menu ==> Findme

Of course you can save the Gmap4 URL as a bookmark in your phone’s browser.

Gmap4 does not save your location or report it to anyone. For more details, please search the Gmap4 Help file on ‘mobile’.

Here are two links with more information if you are curious how this works:

2. You can turn off the coordinates in the lower right corner

Turning off the coordinate display in the lower right will let you see more of the map. You can toggle that display by selecting Menu ==> UTM - LatLng - Off

To open Gmap4 with that display already off, include the parameter ‘&coord=off’ in the Gmap4 URL

3. Tweaking the mobile interface
Gmap4 is not a ‘native’ app for your phone. Instead, the exact same code that runs in the browser on your desktop/laptop also runs in the browser on your phone. Amazing! But this means my options for improving the interface when running on a phone are somewhat limited. What I can do fairly easily is add buttons. However, each button would cover part of the map.

Question: Are there any features of Gmap4 important enough that they should have their own buttons? One obvious candidate is the ‘Findme’ feature. Any others?

4. The MyTopo maps now display ads in one corner. That was not my idea!
For example, this map shows part of Yellowstone National Park:,-110....

The Trimble Company now owns the MyTopo maps. As the 'price' for being allowed to continue displaying the MyTopo maps at no cost, Gmap4 must display Trimble's ad images when the MyTopo maps are on the screen.

Joseph, the Gmap4 guy
Redmond, WA

Trimble are scum-suckers afraid of competition

After the scummy move Trimble pulled with Gaia GPS (GPS app for iPhone and Android), it's a good thing™ that you don't rely on just MyTopo for your detail maps.

Gaia GPS Blog

"Anyone who is capable of getting themselves made President should on no account be allowed to do the job." --Douglas Adams

The Gmap4 code has been

The Gmap4 code has been updated to version 3.0. There are two new ‘big’ features that many people will find useful.

First, Gmap4 can now display a new set of very high resolution USA topographic maps that (1) are a better quality image than the MyTopo maps, (2) do not have heavy watermarks obscuring part of the map and (3) do not have any ads. The link below displays a basic map of the USA. Zoom in to your favorite area (or use the ‘Search’ feature) then open the menu in the upper right corner and select “t4 Topo High”.,-94.2...

You can also set the amount of hill shading you prefer to see on these new maps. Click Menu ==> Hill shading. And there is a new URL parameter (&hillshade=) you can use to set the hill shading in any Gmap4 URLs that you make.

A developer in California named Matt ( produced these new topo map tiles from data he obtained from the USGS. Matt is paying out of his pocket to host these new map tiles on Amazon’s cloud service. It is my great hope that the Gmap4 user community taken as a whole will be willing to make sufficient donations to pay its share of Matt’s Amazon bill. The Menu button on the map has a ‘donate’ link.

Matt’s high resolution topographic map tiles should cover the states show in green on the following index map. I think the states that are not done yet are FL, LA, MA, MS, NH, RI, SD, VT and WY.
As the USGS finishes high resolution scans (660 pixels per inch) for the remaining states, Matt will be processing that data into tiles.

The Gmap4 ‘Help’ file has more information on these new maps and also instructions for how you can report any problems you discover.

Second, Gmap4 now includes a trip planning feature called “Make a map”. You can now click the map to make waypoints, routes and tracks. You can download your work in a GPX file and then upload that information into many handheld GPS units. Of course you can also put your GPX file online and then make a Gmap4 URL to display your file. This feature works worldwide.

Gmap4’s implementation of this feature lets you:
* Click once and create both a waypoint and routepoint
* Edit any data field (including GPS symbol name) that causes information to appear on your GPS screen

“Make a map” quick start:
1. Zoom in where you want to do trip planning
2. Set the map view you want
3. Click Menu ==> Make a map
4. Click a few spots on the map. Distance in miles and kilometers is reported in the lower right corner.
5. Right click any point
6. Click “Download GPX file”
7. Right click the URL to the GPX file and save it on your harddrive
8. Load the GPX information into your GPS

Each click you just made on the map sets a draggable (click-hold-drag) waypoint and routepoint. This is the Gmap4 default for trip planning.

For more information on these features, please visit the Gmap4 homepage and download the current Help file. The sections that describe these new features are marked “(New)” in the table of contents.
Gamp4 Homepage:

I welcome your suggestions for improvements and any bug reports.


Joseph, the Gmap4 guy

Recently Gmap4 was updated

Recently Gmap4 was updated to version 4.1 and now includes a unique map-in-a-link feature that is worth mentioning. Anyone can now make a custom map and save their data right in a Gmap4 link. You do not need to save your data in a separate file such as a GPX or KML file. This may be the easiest and faster way for you to make a custom online topographic map.

To try out this feature:
1. Click Menu ==> Draw and Save
2. Click the map a few times to set draggable symbols and draw a line
3. Rightclick any symbol and select “Gmap4 display long link”

You can copy the link that is displayed, paste it into a new browser address bar, hit enter and your custom map will be displayed.

This feature also works on your iPhone, iPad, android and other mobile device. Remember, Gmap4 is a browser app and your browser has to be online. After you tap the screen to set some draggable symbols then tap a symbol and select “Action Menu”. The list of actions include two different ways to save a Gmap4 link that includes your data.

More information on this map-in-a-link feature can be found in the following three places.

1. What’s new page
Note the tip about deleting the ll and z parameters from your Gmap4 link.

2. Example page
Scroll down to the section titled “Your map data saved in the Gmap4 link”. The examples range from basic to advanced and give you a quick way to see some of the kinds of maps you can make with this feature.

3. Help file
You can download the PDF file and search it (control-f) for the section titled “Make a custom map with Gmap4 and save it”.

Joseph, the Gmap4 guy
Redmond, WA