: Zoom in/out
: Move Map
You can also use W,A,S,D,I,O on your keyboard or the controls on the right.
You can still change Fill Color, click on countries to paint them, etc.
Select the color you want and click on a state on the map. You can right-click on a state to remove its color.
Add the title you want for the chart's legend and choose a label for each color. Change the color for all states in a group by clicking on it.
This map attempts to show all border changes for US States from 1790 to today.
The changing boundaries are represented with a "lifetime" for each State, i.e. a start and end year.
To make sure that each states's changing borders are shown only once, the state of the borders at the end of each year (31/12/XXXX) is used. For example, Oklahoma State was admitted on November 16, 1907 and consequently was already a state at the end of 1907, so the previous entities (Indian Territory and Oklahoma Territory) have an end date of 1906.
The map currently changes with a leap of 10 years, but more dates will be available in time.
You can also check the accompanying blog post for more info.