A city doesn't need to be big to have skyscrapers. It's just a policy choice, like how wide roads are or public transportation. Many Americans are surprised that small European towns are big enough to justify a train station.
California and Indiana both had a population of about 2.7 million in 1916. Indiana had a dense rail network and California didn't. Indiana is only ~5x smaller than California.
This is what the rail network looked like in 1916: