The borders are based on census tracts with low average income. The complete list of zones is here: https://www.irs.gov/pub/irs-drop/n-18-48.pdf https://www.irs

The borders are based on census tracts with low average income. The complete list of zones is here: https://www.irs.gov/pub/irs-drop/n-18-48.pdf https://www.irs.gov/pub/irs-drop/n-18-48.pdf I'm not sure who draws census tract lines.