I was having trouble figuring out why ST_Area area calculations weren’t working correctly in R

I was having trouble figuring out why ST_Area area calculations weren’t working correctly in R. The reason was I was dumb. For ST_Area to work correctly you have to use an equal-area projection, such as Universal Transverse Mercator or Consus Albers. Projections that distort area won’t work, if you want to use such projections, you have to reproject the data before calling ST_Area.