If bird flu is airborne, the government’s current biosecurity-based strategy cannot protect farms on its own. A poultry vaccine likely would have stemmed the damage from this outbreak, experts told me. Yet while other countries have curbed infections through vaccination, the U.S. has not authorized those efforts amid political and economic pushback.

The USDA told me it didn’t investigate whether the wind contributed to the outbreak’s spread.

Here’s how I used genetic markers, satellite imagery, property records, trade notices, wind simulations and Google Street View to do the work USDA did not.