Downloading GIS Data

Your snowmobile map could consist of only the trails. In fact, you can even make a transparent map that will be show over whatever other maps are already loaded on your GPSr. For instance, you could have the trails show up over a Garmin USA Topo or City Navigator map. Some people might even like that better. I decided that I wanted to make more of a self-contained map that had its own lakes, roads, etc. If you want to just do trails, you can skip this (though you might find it useful for acquiring existing trail data from the DNR). Otherwise, read on.

If you're in the U.S., there's a HUGE amount of excellent data available online that can be imported right into MapEdit.

Here's a good place to start: http://home.cinci.rr.com/creek/garmin.htm

He's got links to data sources (seamless.usgs.gov (for roads and other data) and nhd.usgs.gov (for water data) have been the most useful for my snowmobile trail map project) and a guide on how extract and download it and import it into MapEdit. I'll explain what I did below.

You have to decide which data is appropriate for your project, apart from the snowmobile trails. For my map, I decided on lakes and rivers, roads, and towns.

Water data:

I started off with the high-res NHD data (from nhd.usgs.gov) for the lakes rivers and streams, but that ended up being overkill. It was a pain to download it, to import it all, and it was way more detailed than it had to be, which made the map file use more GPSr memory than necessary. You have to download it in individual chunks and not a whole state at a time, so it gets to be quite a chore. If you're making a map of just a small area, though, it would be fine.

If your DNR doesn't have its own data download website, you may be stuck using nhd.usgs.gov. If that's the case, follow the guide above (http://home.cinci.rr.com/creek/garmin.htm) for instructions.

I ended up getting 100k water data from the MN DNR's "Data Deli" since it was less detailed (read: smaller file size) though still accurate, and I was able to download it in one chunk, rather than downloading and importing many files for the NHD data. Unfortunately the Data Deli is only for Minnesota, but look around your state DNR's website and maybe you'll find something. The Minnesota DNR also has all the state trails mapped out and available in Shapefile format which imports right into MapEdit, so that was a lucky find for me. Try contacting your state's DNR to ask if they can provide you with any data.

seamless.usgs.gov does have some water data under the "National Atlas" tab, but it's very inaccurate and not very detailed. It is very convenient to use though, so if you want to just have an idea of where lakes and rivers are and you're more interested in focusing on snowmobile trails, go for it (instructions below).

Roads, towns, and various other data:

Go to http://seamless.usgs.gov . Make sure you don't have your browser set to block popups. You'll need them for this.

1) Click on the "Zoom To Region" button.

Below the map, you'll see three pulldown menus appear. Pull down the "Zoom To State" menu and select your state. If you want to do a smaller region, you can use the other menus, or use the "Zoom In" tool to draw a box around the region you want.

2) Click on the "Download" tab and decide on the data you want to download.

I used "BTS Roads" (under "Transportation" and "National Atlas Cities" under "National Atlas". The National Atlas section has other useful data too, but use the BTS Roads data rather than the National Atlas roads because it's much more accurate. Check the box for each piece of data you want to download.

3) Click on the "Single Template Download" button

Below the map will be a pulldown menu marked "Template:". Select "National Atlas State Boundaries". This will allow you to download the data for the whole state. Now click anywhere in the state and a popup will appear with download links for each piece of data you selected to download. When you click the download button, another popup will appear and let you know when your data is ready. Repeat this for the rest of the files.

4) Unzip all the files and save them somewhere handy.