For a long time, the only topographic maps available for download into hand held GPS receivers were at the 100,000:1 scale, based on the USGS maps of the same resolution. This level of detail is fine if you're driving or flying, but it is really insufficient for hiking. The USGS also has complete coverage of the USA at the 24,000:1 level (the so-called "7 minute quads"), and this is a much more useful resolution for hiking-based outdoor activities. Yet, despite the marketing of both Garmin and Magellan hand held GPS units as hiking gear, neither company released 24,000:1 data for a long time.

This is somewhat understandable in their legacy units, because they were low on memory. When I bought my first GPSr in early 2003 (a Garmin eTrex Vista; top of the line for hand-held units at the time), it only had 24 MB of memory. This was sufficient to hold about half of New Mexico at 100,000:1 but only a very small area at 24,000:1. My current GPSr (a Garmin GPSmap 60CSx) has a removable micro-SD card which can hold an arbitrary amount of map data, limited only by size of the card I put in it^*. Similar upgradeable memory capacity is available with Magellan units. So, given that we now have no significant memory limitations... where are the high resolution maps!?

First, some background on the never-ending conflict between Magellan and Garmin. Bless their capitalistic asses, the two main players in the arena have fundamentally incompatible systems for storing their map data (Garmin uses vector data while Magellan uses raster data). Of course, neither has been willing to make any effort to work with the other to allow for universal map datasets. So once you buy in to either the Magellan or Garmin line of hardware, you are stuck with their map software as well. When I first got into this, Garmin had the better hardware and their 100,000:1 map data was cheaper, so that's the route I took. However, because Magellan uses rasterized graphics for its map data, generating new map data from new map imagery is relatively straightforward for them. Garmin, on the other hand, has to spend time vectorizing complicated map data which can be a very labor-intensive process.

Enter National Geographic TOPO!, a weirdly-named product available from... National Geographic. It is basically all of the USGS topographic maps in five levels of resolution all the way down to 24,000:1 for the entire country. The map data is available on a state-by-state basis, and is obscenely expensive (MSRP of about $100 for a state, though you can find it for about $75 of you look around). Because it is raster data, Magellan was quick to make a partnership with them and now the 24,000:1 data are finally available for Magellan units. Finally!

Of course, this doesn't help me... since I'm heavily invested in Garmin at this point. However, the existence of vastly superior map data over at Magellan is certainly putting the screws to the Garmin folks to offer something competitive, and I'm sure it won't be long now before we see the same data available in vectorized, scalable goodness. Garmin has already released a 24,000:1 product that just covers the national parks, though they split it up into three separate volumes (west, midwest, and east) which is aggravating. Also, some private ventures are doing some of the work for them. AboveTheTimber.com has released the complete Colorado 24,000:1 dataset for Garmin for the price of $80. I see light at the end of the tunnel.

^*Actually, with the 60CSx, the operating system places constraints on the number of map units that can be uploaded (I think it's 500), which actually limits the usable card space to about 600 MB (when using 100,000:1 map data, this accounts for roughly half of the continental United States). Thus, half of my 1 GB card is blank and that really annoys me. I'm hoping for an OS update sometime soon that will correct this arbitrary limitation.