Topo Maps - General question from newbie

The 100k or 24k in the title of the product refers to the scale of the maps, 1:100K (100,000) or 1:24k (24,000), or 1 inch on the map (first, you need to find the zoom level that is optimal, as these scales are devised from old paper maps using the same scales) equals 100,000 or 24,000 inches on the ground.

The GPS maps don't necessarily have a "scale" in that the zoom button changes the scale to what you want. What the numbers REALLY mean is that the detail in the digital map products approximates the detail of the old paper maps of that scale.

So a 1:100,000 scale map gives you a very large, wide view of an area on a piece of paper of a given size. A 1:24,000 scale map gives you a more detailed view of a smaller area on the same size piece of paper. When referring to maps for the GPS, the 1:24,000 scale offers greater detail than 1:100,000 scale. The only reason 1:100,000 scale even exists is because early mapping GPS receivers had very small amounts of memory. New models have a MUCH greater amount and can fit the greater level of detail.

All that said, you don't HAVE to buy maps for a Garmin. Go to www.gpsfiledepot.com and they've got 1:24k detailed maps for a lot of places around the world.

Free maps that allow autorouting (route to a street address) are also starting to show up.

You'd be well-served by buying a blank 2GB micro-SD card to go with that GPS so it can fit lots of maps.