Source: Bureau of Labor Statistics, Census Bureau
This choropleth shows unemployment rates as of August, 2016 with a threshold scale. I employed a mix of command-line tools to transform the fixed-width text file into a CSV, including dsv2dsv:
cat <(echo "id,rate") \
<(tail -n +7 laucntycur14.txt \
| grep 'Aug-16' \
| cut -b 21-22,28-30,129-133 \
| tr -s ' ' \
| dsv2dsv -r ' ') \
| csv2tsv \
> unemployment.tsv
You probably don't have the us.json file (see index.html line 53). This format works on bl.ocks.org but it won't work for you on your local machine unless you have the same file hierarchy.