This map shows mobility flow in France in the last five years. It is based on state and county data. It contains information about flow in more than 45,000 locations.
There are two ways to read this map. The first one is the aggregated map: it shows a reddish color if the overall state population increased in the last five years, and a more blueish color if the population decreased. Clicking on a state will show this information at a county level.
The other map shows mobility flow for a selected state. It gets triggered when a state is hovered more than 2 seconds. In that map reddish states are the ones getting people from the current hovered state and blueish states are states where people moved to the hovered state.
The data can be found in the INSEE internet site. Some insights of the data are found in the blog post.