When looking at prospective land we can get topographical maps of what we are looking at from USGS. You just mail them the coordinates, select what scale you want and then they will mail you a map for eight dollars. A topographical map will include manmade structures, developed trails, roads (both asphalt and gravel), any water sources, and elevation change.
I believe the maps are now available online for free (searching the web)… Here we go: http://ngmdb.usgs.gov/Other_Resources/rdb_topo.html. There are links on that website to purchase the maps and to 3rd party websites for online viewing. As an aside, it would be pretty cool to check out the topo map of where you are currently living. Especially if you live in a hilly area like San Francisco, a topographical map is the near equivalent of a bike map. COOL BEANS.
[Just read that aerial photographs are useful as well, which makes sense. Use google maps or terraserver.com]
While talking about maps I figured it would be good to record on this fine site about hardiness zones. I read some about this while researching orchards. Basically, there are several factors that affect whether a plant will grow in your area, such as rainfall, daytime temperatures, day length, wind, humidity, etc. The USDA plant hardiness map records and separates the United States into different zones depending on average low temperature, which affects whether a plant (or tree) can survive there or not.
Hardiness Map: http://www.usna.usda.gov/Hardzone/
Whoa! Just found a cool set of maps for the western US only that shows alot more information, “since they factor in not only winter minimum temperatures, but also summer highs, lengths of growing seasons, humidity, and rainfall patterns to provide a more accurate picture of what will grow there.” (more…)