Use of the herbicide 2,4-D in the USA to 2019, estimated by the US Geological Survey
US Geological Survey
<a rel="nofollow" class="external free" href="https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2019&amp;map=24D&amp;hilo=L">https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2019&amp;map=24D&amp;hilo=L</a>