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Priest Lake Snowmobile Trails

Current Version: 0.16

Released February 6, 2009 (Revision History)

Download Priest Lake Snowmobile Trails for PC  (292 KB)
Download Priest Lake Snowmobile Trails for Mac  (75 KB)

Have data to contribute? Visit the Switchbacks Data Submission page!

View a Google Map of the Trails

General Information

Priest Lake Snowmobile Trails is a mapset of trails designed for upload to any map-enabled Garmin GPS receiver. In addition to being a mapset, it is also a community effort initiated to record and collect GPS data for the snowmobile trails in the Priest Lake area and provide that data for general public use.


My GPS usage started out in 1995 as a means to map mountain bike trails in my area. Over time I collected a large quantity of track data recording various paths and routes.

Tracks are very helpful when it comes to navigating a route, but the biggest problem with with them is that no GPS can accommodate more than a few at a time. If you are using them for snowmobiling you need to know beforehand what route you want to take and, if you are talking about even a modestly sized network of trails, you have to decide which trails to cull in order for things to fit into your receiver. That's when I started thinking about custom maps for my receiver.

With custom maps like Priest Lake Snowmobile Trails, there is no longer a need to limit the number of trails loaded on the GPS (the maps use only a portion of map memory rather than a limited number of dedicated slots like tracks do). I set out making these maps for my own use and before too long realized that a lot of other people could probably use them, too. That's why I started this web page.


Priest Lake Snowmobile Trails is made to be "transparent", which means that when loaded with other Mapsource products (or the GPSr base map) the trails appear as data laid over the top of the other maps. Priest Lake Snowmobile Trails can also be loaded directly to the GPSr on its own. Custom type definitions (colors) are used to help distinguish individual routes and make them easy to see on the GPS screen when bouncing along on a snowmobile.


The mapset currently covers all of the trails within the Priest Lake Ranger District along with the connector trails between Priest Lake and Schweitzer.

Coverage Map


Below are a few example screenshots of the maps on a Garmin Colorado 400t. The first image shows the Priest Lake Snowmobile Trails layered on top of its companion product, Northwest Topos. The second shot shows the mapset layered on top of Garmin TopoUSA 2008. The third screenshot shows the mapset as it appears on top of Garmin City Navigator 2009. In all screenshots, the terrain shading present in the 400t's built-in TopoUSA 2008 basement is allowed to show through.

GPS Screenshot #1 GPS Screenshot #2 GPS Screenshot #3


The installation of Priest Lake Snowmobile Trails is straightforward. It can be utilized from within Garmin's MapSource software (on PCs) or uploaded directly to your GPS unit (using freely available utilities).


The accuracy of the data used to create these maps varies greatly. These maps are to be used for reference purposes only. The author(s) are not responsible for any inaccuracies and no responsibility is assumed for damages or other liabilities due to the accuracy, availability, use or misuse of the data presented. Installation and use of these maps is at your own risk!


For use from within Garmin's MapSource (on PCs), download the zip file from the link above, unzip it, and then execute the mapset installer. This program will install the map files and register the mapset with MapSource. Within MapSource a new mapset product entitled "Priest Lake Snowmobile Trails" will be available in the Product drop down selection list (or from the View | Switch to Product menu option).

For use with Garmin's RoadTrip (on Macs), download the .tgz file from the link at the top of this page, unarchive it into the resulting .tar file, then unpack that to a .gmapi file. This file can then be installed into RoadTrip with MapManager and onto the GPS receiver with MapInstall.

GPS Usage

The Priest Lake Snowmobile Trails mapset should overlay any other mapset present on your GPS unit. It is important to note that when you upload maps to your receiver, the existing mapset on the unit will be deleted. This means that if you want Priest Lake Snowmobile Trails to overlay Northwest Topos maps, for example, you will need to upload the Northwest Topos map along with Priest Lake Snowmobile Trails all at once. To switch between mapsets (if more than one has been loaded to your GPS) simply toggle the hide/show settings for the desired mapsets on your receiver.

Support this Effort

If you find Priest Lake Snowmobile Trails useful and would like to see more data added, or new mapsets created, please consider supporting this effort in one (or more) of the following ways:

Feedback & Referrals

All feedback (comments, corrections, questions, etc.) is welcome and encouraged. Please direct all feedback to the email address shown at the top of this page. I try my best to reply to every email I receive but it is not always possible. I do read every email and appreciate the feedback.

If you like this mapset please let others know about it. More people using and supporting this effort means more additions and corrections are possible.

Data Contribution

The core of all of these mapsets is data. The real heart of that data is tracks recorded out in the field with GPS. Since data of this accuracy is hard to come by from government and other agencies, and I cannot possibly get out there and ride all of the trails at Priest Lake in a reasonable amount of time (although I'd like to try!), that's where you come in! Any track data you can supply is needed and most appreciated, and will be integrated into the mapset for everyone to use. Data submission is available at the Switchbacks Data Submission page.

If you would like to collect and submit your track data to the project, please follow these pointers so that your effort can be as useful as possible:

  • Before you start recording track data, access the Setup menu for your GPS receiver and adjust the recording frequency and quality set of your track recording to the best available. On my unit I generally set the recording method to "Auto" and the recording interval to "Most Often".
  • Turn on the GPS receiver and allow it to have a clear view of the sky for at least 15 minutes before you begin recording. This allows the unit to connect with as many satellites as possible, which increases accuracy and helps it to maintain satellite lock.
  • Hold or place the receiver in a location where it can best receive satellite signals as you travel. Be aware of where the antenna is located and the best orientation of the GPSr for signal strength. Patch antennas like those on the eTrex models work best when oriented horizontally, while quad helix antennas like those on the 60 series receivers tend to work best when pointed straight up.
  • Avoid saving the track to the unit's internal memory before downloading. That reduces the number of points in the data and subsequently reduces the precision of the track.
  • Send me the track log with the name of the trail(s) recorded and information on the type of trail (e.g. paved trail, dirt trail, unpaved road, etc.). GPX is the preferred format, but I can convert most formats.
  • Also send along any waypoints along the route like trailheads, attractions, or summits.

Monetary Contribution

This mapset is free to download and use but if you find these maps useful please consider making a donation to help offset the costs incurred in producing and offering them (software licenses, website hosting, etc.).


Data Sources

In addition to GPS tracks recorded over the years, the datasets utilized for creating Priest Lake Snowmobile Trails include the following sources:

  • Mike Sudnikovich
    Provided GPS data for many of the snowmobile trails in the district.
  • Janet Elliott
    Provided GIS data and support for the Priest Lake groomer routes.
  • USDA Forest Service
    Provided GIS data for other snowmobile trails in the Priest Lake area.


Several software applications are used in the production of this mapset:

  • ArcGIS
    Used to merge and cull datasets and edit fields.
  • Global Mapper
    Used for the majority of data manipulation and for digitization of paper maps.
  • cGPSmapper
    The primary tool for compiling the data into a Garmin map file.
  • GPSMapEdit
    The visual interface that handles import of the data and export into a form that can be compiled by cGPSMapper.