# A More Complete Explanation of the Hike Location Maps

See Explanation of Maps for a brief introduction to the region maps. This page presents the same information more clearly, showing a series of maps that start with a map showing only road information, and then gradually adding more information to arrive at the final map. The map order is:

• A conventional map showing the SGM;
• Just the roads in my map, with labels;
• Just the hikes;
• Hikes and roads with labels;
• Hike region definitions overlaid on hikes and roads with and without labels; and
• A larger scale map of the last item which omits the few hikes in the northwest portion of the SGM.

The general vicinity of the San Gabriel Mountains (SGM) is shown in the following map from Vicinity Corporation. The cross is near the Angeles Crest Highway (SR2), the main road through the SGM heading northeast from above the "a" in "Pasadena". SR39 is the road just to the east that no longer meets SR2 due to a massive landslide. Note the surrounding roads to compare with my maps below.

## Map from Vicinity Maps

Click on the map to go to Vicinity Maps

The following map shows just the roads within and around the SGM. The roads have been digitized by me from the USGS maps, and so don't follow every nuance of each road. I've only plotted the minor roads which lead to trailheads. In some cases, the minor road continues on past the trailhead shown.

The axes are north latitude and west longitude in degrees. Note that USGS maps for the U.S. plot east longitude which is (360° - west longitude). I use west longitude so that my spreadsheet would plot the roads with west on the left.

The map is not a true-scale map since north-south distances are slightly different from east-west distances. One tic mark (0.1°) of latitude is 11 km = 6.9 miles, and one tick mark (0.2°) of longitude is 18 km = 11.5 miles. Since the tick marks span 56 pixels in latitude and 73 pixels in longitude, the scales are 0.12 miles per pixel in latitude and 0.16 in longitude. The difference in scales is thus about 25%.

The digital data for all plotted items is available on request, and will separately soon for those who would like to have them.

## Map legend

SymbolItem
Red lineAngeles Crest Highway
Black linesCity streets

The following map shows just the trailheads for hikes in the SGM.

Now let's put the trailheads on top of the roads (or more precisely, at the ends of a lot of the roads). As you might imagine, the trailheads mostly follow the major roads and the foothill locations next to civilization.

Now let's superimpose the hiking regions and make the map clickable so that a click within any hiking region will take you to those hikes in that region. Look at the browser status bar at the bottom of your screen to see what area your mouse is over.

Map legend:

SymbolItem
Red lineAngeles Crest Highway
Black linesCity streets

This map can be made less cluttered by removing the labels, but is now useable only by those who know the region from the previous map:

In order to see the detail better in most of the SGM, the following map excises the trailheads for the few hikes in the northwest SGM, but leaves in that clickable region to allow those hikes to still be reached.

And finally, the labels can be removed from this map as well:

With a less-cluttered map, I can plot some other interesting things, like the locations of waterfalls and of sites with remaining wreckage from airplane crashes (thanks to Chris Killian). Waterfall locations are represented by filled small blue-green triangles, and the crash sites are represented by small green open squares.

I've also made a plot of all the waterfalls and crash sites with labels in the entire SGM. The waterfalls and crash sites are shown in each of the hiking region plots as well, where they can be seen much better.

Go to Hikes in the San Gabriel Mountains