It means you would have to have a massive law enforcement presence, where law enforcement officers would be going school to school, home to home, business to business, rounding up people who are undocumented.
问题:
1.where…是什么从句,怎么理解?
2.school和to school是单独的2个状语吗?
3.rounding 是并列going还是伴随状语?