Steps to making the borders map
- get county polygons
- create segments of county borders from each polygon using qgis
- use the intersection tool in qgis to assgin 2 county geoids to each line segment
- export results to use in mapbox
- import vaccination data from cdc
- calculate difference in rates between the pairs of adjacent counties for each line segment
- set the color and thickness of each line segment based on the difference in vaccination rates