This makes it easier to see what state or province a particular event may belong to. The state data was extracted and formatted from Natural Earth Data (www.naturalearthdata.com). More specifically, the data was extracted from http://www.naturalearthdata.com/download/50m/cultural/ne_50m_admin_1_states_provinces_lakes.zip The data was converted to GeoJSON and "minified" using the procedure outlined at http://www.extendi.it/blog/2014/5/15/29-creating-a-world-map-geojson
This prevents the user from panning the map to far in any direction. It is a workaround to the fact that OpenLayers 3 does not support wrapping the world when using a Vector layer. This commit works by setting the "extent" option on the View. This is an experimental feature of OpenLayers, but it seems to work well enough. The feature works by setting the upper and lower bounds on the center of the map. I had to experiment to find a set of values that would help keep most of the map visible while also allowing the user to zoom in on locations near the edges of the map (such as Hawaii and New Zealand).