Overview maps normally have a scale of between 1:50,000 and 1:100,000, meaning that one unit on the map (e.g., an inch, a centimeter, a thumbnail) equals 50,000 or 100,000 units in the field. While planning a trip, use these small-scale maps to develop a general understanding of the landscape, including the main watersheds, road systems, and trail networks. They aid with identifying a general route and potential alternates and working through logistics like travel, permits, and resupply points.
In the field, overview maps are useful for pinpointing distant landmarks and serving as a reference for mid-trip planning discussions, self evacuations, and detours.
In the U.S., the gold standard for large-scale maps is the now digitized US Topo series, produced by the USGS. US Topo maps are modeled after the pre-digital 7.5-minute quadrangles.
Each paper quad—about 55,000 were originally made—represented 7.5 minutes of latitude and 7.5 minutes of longitude.This equated to about 8.5 miles of latitude (the map height) and about 5.5 to 7.5 miles of longitude (the map width), since the physical distance between lines of longitude decreases toward the poles.
The USGS quads have a scale of 1:24,000. One inch on these maps equals 0.3788 mile, since there are 63,360 inches in one mile. The most common contour interval is 40 feet.
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I am Jeff Clark, founder of Internet Brothers, producer of this blog, and passionate about hiking. I live in Western NC near the Blue Ridge and Great Smoky Mountains. Pisgah and Nantahala National Forests are just out my door, so the content will focus on these areas, but let me know what you would like to see on the site. 
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