Making Choropleth Maps using GeoCharts

Data visualization tools come in handy for mapping data sets, this post focuses on using GeoCharts in the Google Charts library to create borders for United States data on a state-level basis. This data is using state interstate speeds and maps out which states have the lowest/highest speed limits across America.

As you can see in the GeoCharts below, the speed limits are for cars in the first map & the second map uses truck speed limits. There’s some variation from state to state between car & truck speed limits; however I normalized the color scheme of the maps so that it’s easy to compare the values from one chart to the other.

Here the map of Car Speed Limits on the Interstate:

And here is the map of Truck Speed Limits on the Interstate:

At first, I thought it’d be a good idea to look at public data on highway crashes & fatalities, however a lot of the publicly available highway data is a few years old and it just wouldn’t make sense to try to compare speed limits from 2013 with highway accidents from years before then. It might make for an interesting side-by-side map, but it wouldn’t really be a great indicator of speed limits correlating with highway data.

It can be difficult at times to find clean datasets, however I found this information from the U.S. Department of Transporation, link here.

For a quick comparison here’s a smaller version of the maps to see all the states:

Check out these awesome links for transportation data:

The link for creating GeoCharts can be found here, using Google’s documentation.

I’d like to create more charts like this, since choropleth maps are a great method to creating digital maps. They are used to depict geospatial information efficiently and are a commonly-used map for displaying hotspots for trends.

As seen here, Google Trends uses GeoCharts to display common search results for terms, a choropleth GeoChart map visualizes popular areas relative to certain keyword searches:

These two Geocharts are used to display both state borders lines as well as metropolitan areas. This is a feature of Google Charts and is implemented on these Google Trends embeds as well.

Whether you want to display maps for your personal website or want to learn more about data visualization techniques; creating professional choropleth maps is a great method making high-quality digital maps. The quality of the map depends on both the cleanliness of your data (easy to implement) & the creativity of your web design skills.

Overall, this map has been one I’ve been wanting to create for a while and it ought to be a great template to have for any future projects involving state-level data.

If you have any questions or comments, please send an email: will[at]


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