Go ahead and play around with the map above (created by activist Kris Banks), showing the precinct-by-precinct outcome across Harris County for last month’s Republican presidential primaries. Shades of red show the spots won by Cruz (most of them, though a lighter shade indicates less solid support). Precincts won by Rubio show up in shades of blue (mostly clustered on the west side of the Inner Loop), while Trump support is marked in gold (mostly northeast and south of Downtown, as well as strung out along the Westpark Tollway); a few Carson precincts show up in green.
January Advisors’s Jeff Reichmann recently took a look at Banks’s election maps, which include results from both parties’s primaries and a starkly geographically-split down-ballot race for the Democratic district attorney nomination. You can click on each precinct to get its number and a breakdown of the results. Here’s how things looked for the Democrats, with the Sanders precincts in green spangling a field of Clinton blue: