Wisconsin ranks 25th in population density. Texas, the densest state which has gone for Cruz, is 26th. The densest state Cruz won without a home field advantage was Oklahoma, which ranks 35th. Missouri was 28th. North Carolina, the only state not yet mentioned where Cruz came close to knocking off Trump but still finished second, was 15th (a slight outlier).
Cruz should get a decent amount of delegates in Wisconsin, but shouldn’t win, going by past performance.
Higher population density states have more to fear from illegals (job stealing, general criminal activity) and Muslims (terrorist attacks). Trump has been more proactive than Cruz against existential threats, while people in low population density areas such as Wyoming can afford to somewhat ignore these threats. (I don’t think Cruz voters, or most Trump voters for that matter, recognize the dangers of Cruz’s GOP-e ties.)