The Dome was a gigantic glass dome placed over Springfield by the Environmental Protection Agency due to it being the most polluted town in the world. It was a crisis so bad it had its own name and theme music dubbed Trappuccino.
The dome could easily crush people when coming down as one unfortunate person found out. It had to be transported by a fleet of helicopters with suction cups.
It could only be damaged after numerous repeated attacks such as Stampy hitting it. There also would have been a way to create a hole with Jonathan Frink's Acid Shooting Ray - which was on the other side of the dome. The dome also had a massive, seemingly-invisible screen that Russ Cargill could communicate with.
The dome was finally destroyed by Homer and Bart Simpson on the day Springfield was to be blown to smithereens to make a New Grand Canyon. Homer rode a motorcycle around the dome with Bart throwing the bomb out of the hole on top which was previously plugged up. The bomb destroyed the dome but not the town itself.
A long time after the dome was destroyed, Charles Montgomery Burns made another one. He was going to lower it onto Springfield, but everyone reminded him it had already been done. Burns then left dejectedly.
- According to Kent Brockman, Springfield was under the dome for 93 days.
- It is unknown why the residents of Springfield didn't dig a hole under the dome. A possibility is that as usual, they weren't thinking. However, Cargill ordered "roving death squads" to watch the dome after the Simpsons escaped being lynched for Homer's role in the town's confinement, so perhaps anyone who thought of escaping would've been deterred.