Create a Multi-layer Map in Drupal 7 with Openlayers 2.x
There are many tutorials out there for creating maps in Drupal but most of them focus on just one layer on a map. This tutorial is for creating one map with multiple, switchable layers complete with pop-ups and a title. In the future I plan on writing more tutorials on more advanced mapping topics, such as polygons, using kml files, and other items. For now though, below are the main steps and concepts to understand with OpenLayers: