When I lived in Texas, we had a massive storm in winter of 2021 leaving many without power for a week.

I was told that Texas maintained its own energy grid independent from the rest of the nation’s eastern and western grids, and supposedly only had a handful of high-voltage DC lines running between Texas’s and the rest of the nation’s. Supposedly this was why we couldn’t rely on excess capacity from anywhere else in the nation while our power generation capability was down.

But this map doesn’t seem to show Texas as isolated - there appear to be many lines in and out and no clear separation?