How was the Pullman Illinois unique from any other city?
The city was based on the Pullman factory there.
Pullman Company was a factory that produced top of the line luxury railway passenger cars.
The corporate bigwigs at Pullman Co. wanted to make as much profit as they could. One way they did that was to create and build a city around the factory. Families lived in the city that also worked in the factory. Pullman Co. could also tax the citizens as well, making them more money.
Pullman has been compared to Chernobyl, a city where almost the entire population is related through a company or factory. Many companies in this era did anything possible to expand their profits, even if it meant building an entire city to gain a profit.