Why don't USGS 7.5 minute topographic maps show the UTM grid?
For maps in the Historical Topographic Map Collection (1884-2006): Through time, policies have changed regarding whether or not a full UTM grid would appear on the 7.5-minute map series. Beginning in the mid 1950's, the grid was indicated by blue ticks around the map at 1000 meter spacing. In 1979, the ticks were replaced with a full-line black UTM grid. This decision was reversed in 1992, then reversed again in 1994, but the 7.5-minute topographic program was winding down by this time and relatively few maps were affected. Maps published over National Forests in cooperation with U.S. Forest Service do not show the full grid regardless of their vintage.
For US Topo maps (2010 and later): All US Topo maps have a full UTM grid that is implemented in conformance with the U.S. National Grid (USNG) standard. Because US Topo maps are published as layered PDF documents, users have the option to turn the grid off.
Learn More: Military Map Reading 201 - UTM vs MGRS