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Gmap4: Great Online Topo Maps and Map Sharing for the USA and Canada

Gmap4 Topo Maps and Online Sharing Tool
Gmap4 Topo Maps and Online Sharing Tool

Gmap4 is the free online mapping tool that I use for planning hike, backpacking, and bushwhacking trips. I like it because it has some of the most accurate digital maps available online and lets me rapidly compare different maps from several different sources. That is probably the most important feature for me because so many free and commercial digital online maps are so out of date, a problem I’ve written about previously. Being able to compare older ‘historic’ maps, aerial and satellite images, and up-to-date digital maps in one tool helps me determine the best route for my hikes. (I still refer to local printed maps, which are still the most up to date, but harder to plan a route with). 

But there are many other features about Gmap4 that make it very attractive for collaborative trip planning and sharing your maps with other people, including the following key capabilities:

  • Display grid lines
  • Display lat/lon or UTM coordinates
  • Display current magnetic declination
  • Read and display data from KMZ, KML, GPX, TPO, TXT, and Google MyPlaces files
  • Save GPX files
  • Change the amount of hill shading
  • Route sharing using hyperlinks only – no files or applications needed!

Gmap4’s Maps

Gmap4 Home Screen and Map List
Gmap4 Home Screen and Map List

Gmap4 provides users with a wide collection of different maps to choose from, including:

  • Street map from Google
  • Aerial photo from Google
  • Aerial plus street names from Google
  • Aerial photo from U.S. Department of Agriculture
  • Terrain from Google (default)
  • Topographic map from MyTopo (USA 1:24,000 & Canada 1:50,000)
  • Topographic map from USGS via “The National Map” service
  • Topographic map from CalTopo.com & USGS (USA 1:24,000)  – Best Quality
  • Topographic vector maps for Canada
  • USA topographic maps from ESRI. Zoom level 12 shows a very nice map for a relatively large area.
  • Worldwide topographic maps from ESRI
  • Worldwide topographic maps plus crowd-sourced trails from OSM Cycle
  • Worldwide street maps from OSM
  • Earth with Google earth browser plugin

Topographic Maps Included

Of those maps, the subset of topographic maps most relevant to hikers is described below. I use the map labelled t4 Topo High USA the most because it’s the most up to date for the areas of New Hampshire that I hike in. I can tell this because it does not include trails that were removed from the local trail system, washed out by floods, or closed due to landowner disputes.

  • t1 Terrain: This is the same terrain map you see if you use POGM (Plain Old Google Maps). For the USA the contour lines appear to match the contour lines on the 1:24,000 scale USGS topographic maps. For Canada and many other countries the contour interval is 20 meters. Some countries do not have topographic data available.
  • t2 MyTopo: These are medium resolution scans (pixels per inch not published) of the 1:24,000 scale USA topographic maps and 1:50,000 scale Canadian topographic maps. This map set also includes the U.S. Forest Service updates including USFS road numbers.
  • t3 Topo USGS: These are relatively low resolution scans of the 1:24,000 scale USA topographic maps. These maps are provided by the USGS via a project called “The National Map”. In a few places these maps show old trails that do not appear on the other topographic map sets that Gmap4 displays.
  • t4 Topo High: Most of these maps are high resolution scans made at 600 pixels per inch (ppi) of the 1:24,000 scale USA topographic maps. Some maps were scanned at 400 ppi.
  • t5 Canada: This is a new type of map that is based on ‘vectors’. If you zoom in you will see that the topographic lines are not smooth curves but instead are a series of short straight lines. These maps are provided by the Canadian government and you can learn more here: http://atlas.nrcan.gc.ca/site/english/maps/topo/index.html

How to Share a Route in Gmap4

Link to Gmap4 Route
Link to Gmap4 Route

Here’s a backpacking route I created for hiking to a remote peak named North Isolation in the White Mountains that’s on the Trailwright’s 72 peaklist. The route runs along the Mt Stanton and Mt Parker Trails instead of the normal Davis Path route. Just click on this hyperlink and the route will be displayed in our browser (the waypoints are encoded in the hyperlink.) You can also create a GPX file within Gmap4 and share it that way.

This is the map (below) you’ll see displayed in your browser when you click on this link. You don’t need to load any software because Gmap4 is a browser-based app. This means that native, device specific apps are not available to use it, but it runs in many different browsers so you should still be able to use it. For example, I can run Gmap4 on an iPad running Chrome as long as I have a live Internet connection.

t1 Terrain (default)
t1 Terrain (default)

You also have the option of viewing the route in the other maps provided with Gmap4. For example, try switching to  the Aerial Google Hybrid map (as shown below) in the rightmost pull-down menu to see a different map of the route using the same waypoints. This feature is quite helpful if you want to compare a Topo view to an Aerial view with vegetation.

Aerial Google Hybrid Map of North Isolation Route
Aerial Google Hybrid Map of North Isolation Route

How to Plan a Route and Share it

Here is a quick illustration of the process you’d go through to plan and draw the North Isloation hiking route we shared above.

Search for Isolation Mountain, New Hampshire
Search for Isolation Mountain, New Hampshire

1. Search for Isolation Mountain

We search for Isolation Mountain and not North Isolation because the latter is rarely marked on maps. North Isolation is located just north of the intersection between the Davis Path and the now-closed Isolation Trail. 

Draw and save waypoints
Draw and save waypoints

2. Draw the Route Waypoints from the Mt Stanton trailhead to the North Isolation summit.

Name Waypoints, Route, etc. or Create GPX file
Name Waypoints, Route, etc. or Create GPX file

3. Name Waypoints, Route, etc. or Create GPX file

I mainly print the maps I create with Gmap4 so I never bother labelling my waypoints. But it’s probably a good thing to do if you want to publish a route for GPS users.

Create GPX file display or download
Create GPX file display or download

4. Create Viewable GPX file or download

Print Preview
Print Preview

5. Prepare the map for printing.

I like having gridlines on my map and a current declination so I add them before I print out the route.


Gmap4 is a very powerful online mapping tool that provides excellent quality maps and easy to use hyperlink-based map sharing tools. It’s fantastic for sharing a route with other hikers before a trip because they don’t need any software to view or print it and for planning out off-trail adventures where having a variety of different maps types at your fingertips is very powerful. But for all of it’s strengths, Gmap4 is a little rough around the edges when it comes to usability. Still, if you’re already messing around with GPX files and GPS receivers, you’ve already gotten your hands dirty and may find Gmap4 more inituitive than many other tools available. Personally, I love Gmap4 and I love the fact that it’s free.

To learn more about Gmap4, visit the Gmap4 home page at http://www.mappingsupport.com/p/gmap4.html. Please also consider making a donation to help support this application.

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  1. Thanks, Philip. I’ll be putting this to good use.

  2. My father was a navigator on a B-24 in WWII. After the war, he embarked on a long career in geophysics, which included much mapping and surveying. He taught me map and compass skills when I was a small child and used to take me to the lake to practice surveying and map making with a lensatic compass and notebook. I grew up around topo maps and have file cabinets full of them, including his WWII aviation maps of the Pacific Theater.

    For me, a topo map is like having a fine book to read–I can take many journeys on a map and have found all kinds of cool places to visit from them. In central Texas, the Willow City Loop is a ruggedly beautiful drive, especially popular in the spring when the flowers are blooming. I had been driving that loop for decades before it became an official scenic route. Studying topo maps, I found a route using obscure back roads that wound among towering granite prominences. It became a standard route for me whenever I was in that part of Texas. Then, one year, I saw the signs identifying my secret scenic side trip as the “Willow City Loop”.

    I’m going to enjoy (i.e. waste a bunch of time) on Gmap4.

    • If you really want to “enjoy” yourself, check out the Gmap4 GIS page. I’m too lazy to use it and prefer the core functionality, but you can really do a lot of special stuff if you want to invest the time.

  3. This is great! I’m already using it in negotiating a 4 day Colorado backpacking route with a friend living in another state.

    Thanks Phillip!

    • Jim – The collaboration potential for negotiating routes is really exceptional. I like the fact that you can just send a hyperlink to someone and have it render without the need to fuss with GPX files or other map formats.

      Me and my English friend Martin used two different mapping tools to plan our recent Scotland hike, and boy, it was a pain in the ass to share GPX files to plan that route. I wish we could have used Gmap4 instead, but we were using UK ordnance survey maps that are not part of the system currenty.

      Spread the word about Gmap4!

  4. I have been using this for a while, and appreciate this posting as it will help me get more functionality out of the product. Thanks!

  5. Philip – Thanks for the kind words about Gmap4. I am real close to updating the production code with new features. When that happens each map will include a link in the lower left corner to the “What’s New” page. More cool ideas are in the works. It is certainly a fun time to be an online map developer.
    Joseph, the Gmap4 guy.

  6. Thank you for the overview! I’ve looked for free mapping tools but have never found any that were very useful – but Gmap4 looks like it will be a great resource!

  7. I’m surprised I haven’t seen this before on here. Must have overlooked it. I’ve been trying to find a nice online mapping tool and route planning app. So far I’ve just been using a combination of the Trimble Outdoors Android app for marking way points, and using caltopo for looking at topo maps of the area. I’m definitely going to play with this for a while today. I’ve been obsessed with Open Street Maps lately. In particular, the open cycle map.

    • Shawn. Caltopo now has collaborative capabilities too. I discovered Caltopo after G4maping and I use it almost exclusively for shorter trips now, especially bushwhack planning. because the printing is so superior.

      • There is definitely some cool features to caltopo that is for sure. I know what you mean by printing. Being able to save to a pdf first and then print makes it a bit easier instead of just printing what is on the screen. One of my favorite features of caltopo is the ability to blend different maps together. I guess the point is take a look at multiple sources and see what works best for the situation! With that said, I also have about 5 different Android apps installed that I’m testing and playing with. They all have their own strengths and I can’t settle on just one. I definitely am not one to rely on digital maps exclusively. That is a recipe for disaster. Thanks for the info!

  8. I see that this posting is a few years old, but still thought I would comment.

    As I write this, January 2016, Caltopo is superior to the Gmap4 in many ways, and it’s nice to see Philip recommend Cal topo.

    Specifically, printing is much easier.

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