Order [book in series=yearoffirstbook.book# (eg 2014.01), stand-alone or one-author collection=3333.pubyear, multi-author anthology=5555.pubyear, SFM/MM=5000, interview=1111]: 1971

The World Inside by Robert Silverberg

In the year 2381, the Earth contains 75 billion people. Despite the dire warnings of 20th century prophets, humans have not exhausted the Earth’s resources. There is plenty of food for everyone, but because 90% of the land must be covered in farms, most of the people live in Urban Monads — 1,000-story skyscrapers housing 800,000 people each. Citizens aren’t allowed out of their building, and many aspects of society are rigidly monitored. Everyone is married at age 12 and each couple is encouraged to have as many children as they can because fertility and children are blessings from god.