And something strikes me about the H. If you look at ethnicity inside the loop, it follows a textbook sectoral distribution, with clearly discernible boundaries at major rail lines:
But this pattern fades as you move further out. Here’s a chunk of Alief / West Houston:
There’s just no discernible pattern at all. A few individual apartment complexes are predominantly one ethnicity, but the area as a whole is thoroughly mixed. Mission Bend (top left) is particularly heterogeneous.