Today, with even the great grande dame Carson Pirie Scott gone, it's hard to remember that State St was once packed with retail boutiques and department stores.
Consider the block directly south of Fields:
That's Field's on the far left, the Columbus Memorial Bldg (some retailers but also offices), then Chas A Stevens, then Mandel Bros, then Carson's on the far right at the corner of State and Madison. And that's just one side of one block!
What's even more amazing is that this density of retail didn't come about as a result of mere competition. Field himself (as in, Marshall #1) purchased chunks of real estate and sold it to other retailers, hoping to draw more retail business to the area around his store. The thinking, not unlike that for a mall today, was that the more shops were concentrated in one area, the more likely people will come to that area to go shopping.
I think the mobility that cars gave us has made us forget just how much of a virtue this was in the days when trains, trolleys, streetcars, and horse-drawn buggies were the major modes of transportation.
And helps us understand why the arrival of the automobiles (making it so much easier for people to go wherever the wanted to shop) and the continuing increase in population in Chicago (making it more and more congested on State St) ultimately spelled trouble for State St.
But nonetheless, for a brief while, luring other department stores and boutiques to the area around his store was a brilliant strategy for Field.