Topographical maps give contour lines and other important details for crossing a landscape. You’ll find them invaluable on a hike into the wilds. The contour lines’ shape and their spacing on a topo map show the form and steepness of a hill or mountains, unlike the standard road map and most brochures and handmade trail maps. You’ll also know if you’re in woods, which is marked in green, or a clearing, which is marked in white. If you get lost, figuring out where you are and how to get to where you need to be will be much easier with such information.For some day hikes, though, this is information overload. If there’s only one clearly marked trail on a flat surface, a topo map isn’t all that necessary. Another disadvantage is if going on a long hike, you will need a couple of sheets or a large topo map to show the area where you’re going, and this can be a bit cumbersome, especially in a breeze.
In addition, some U.S. Geological Survey topo maps are out of date and may not give the most current forest road or trail numbers.
Private companies often offer more up-to-date topo maps of major hiking areas like national parks. Still, for remote areas such as national forests and BLM land, USGS maps tend to be accurate more often than not as the landscape hasn’t significantly changed in decades.