The problem is that there are way too many geographic units to cleanly divide a state, unless a partisan gerrymander is your goal. Census blocks are adored by gerrymanderers because they allow maximum manipulation in the name of population equality. Even block groups and precincts are too numerous for congressional districts.
Last decade we did a simple
study using counties and towns that I turned into a graph. The vertical axis is a log scale where 0 is a maximum range of 1 person (ie exact equality), 1 is a maximum range of 10, 2 is a maximum range of 100, and 3 is a maximum range of 1000 persons. Ranges that large have been permitted by SCOTUS when a state strictly follows neutral redistricting principles.
You can use the graph to determine how equal you want the districts to be, then find the average number of geographic units on the horizontal axis. For example if you want 4 districts to be within 100 persons of each other you should plan on having 4*24 = 96 units (hello Iowa). The muon rules started with this and then built in more sophisticated measures so that if the number of counties is too small, one can keep the chopped counties at a minimum and make reasonable tradeoffs for compactness.
