Re: Using a Topo Map in the Woods

The only real way to check the accuracy of the map is to get out there and use it. Sometimes there is a reliable guidebook to the area (note I said "sometimes" - there are some notorious guidebook errors, too). Keeping track of your location all the time helps get around the map and guidebook errors. Talking to the local land manager (ranger for state and federal parks and forests, similar for BLM) can often get good info. There are websites that post map corrections or GPS-derived tracks (NatGeo's Topo! has such a page, and their Trails Illustrated map series have field-checked trails on them).

Mainly, it is just a case of making note and keeping track of landmarks as you go, and talking to people familiar with the area (other hikers, rangers, local guides and packers). These people will have current information that you should have anyway - passes blocked by snow or rockslide, streams that are easily fordable or impassable due to high water, bridges that are washed out, current info on dangerous wildlife (including 2-legged "herbal" farmers who carry and use "heat"), availability of water at the "usual" watering and camp sites, etc etc. Take notes on your map, as has already been suggested.

Oh, sorry, you asked about date of the map ....... excuse me while I get up off the ground from laughing so hard. The date label only tells you when someone quit working with the data from a survey that applies to some random part of the map, because they had a publishing deadline.

I guess I shouldn't be quite so hard on the map folks. The USGS does a pretty good job with maps in the 50 states and the territories - far better than 90 percent of the countries in the world and equal to the other 10 percent. Given the limitations of time, personnel, funding, and the continually changing landscape (new roads and trails, re-routing old roads and trails, abandoned roads and trails, floods, erosion, volcanic outbursts [I have before and after maps of St Helens, to commemorate my before and after climbs of that hill], etc etc), they actually do a superb job. It is hard work, even given modern surveying tools. If you want to see how bad maps can be, try some of the 3rd World countries. There is still a lot of this planet that remains to be mapped (a friend of mine is engaged in a mapping project in Antarctica - he has spent the past 4 or 5 daylight seasons clambering all over just the Sentinel Range, carrying a survey-quality GPS receiver to as many peaks and passes as possible, then post-processing the data to get the accuracy to an acceptable level. He and his team are doing a superb job, under really difficult working conditions. But at least, he doesn't have an African or South American jungle to contend with, or some huge desert - the Sahara still is not completely mapped).