Look, it's completely obvious why the Enterprise is being built in Iowa.
Midwesterners are still mad about the Klingon who crashed in the cornfield in ENT's first episode, "Broken Bow." So they built a giant starship in the corn as a "scarecrow" to keep the Klingons away. They even named it "Enterprise" after the first ship to go screw with the Klingons. This also explains why country boy Kirk hates Klingons so much when he grows up, because they keep ripping up cornfields! And to add insult to injury, after they ripped up his cornfields, then they killed his boy! Ingrates!