Aereo will be expanding its live TV streaming service to Chicago on September 13, CEO and founder Chet Kanojia announced today at TechWeek Chicago, now bringing the number of operational markets to four total.

Aereo most recently went live in Atlanta on June 17, having already expanded to Boston in May from its home base in New York. The rollout in Chicago covers an area of 9.5 million people, so it’s the biggest market outside of New York for the upstart streaming service. It will be available across 16 counties in Illinois and Indiana.

In Chicago, major networks like WLS-TV (ABC), WFLD-TV (FOX), WMAQ-TV (NBC), WBBM-TV (CBS) and WYCC (PBS) will be available, along with Bloomberg and other over-the-air special interest and foreign language channels.

Aereo uses the Internet to stream live over-the-air TV signals to subscribers who use its unique antenna, and they can watch on a computer or compatible mobile device. The service also has DVR features that let subscribers pause, rewind and fast-forward through programs, and even record them for later viewing.

Counties in Illnois that will be able to use the service include, Cook, DeKalb, DuPage, Grundy, Kane, Kankakee, Kendall, La Salle, Lake, McHenry and Will. In Indiana, Jasper, La Porte, Lake, Newton and Porter will be eligible.  

It’s unclear what reaction, if any, networks will have to this latest expansion, having already waged an ongoing legal battle to shut Aereo down. Part of the dispute stems from the fact Aereo doesn’t pay retransmission fees to the networks it streams, and that there are no agreements in place on ad revenue from commercials played on those channels. Fox and CBS have threatened to pull their OTA signals and go cable-only if Aereo isn’t made to stop its operations by the courts.

For Aereo, it seems it’s business as usual, where the service offers a membership starting at $8 per month for access and 20 hours of DVR storage. For $12 per month, subscribers can upgrade to 60 hours of storage. There is also a 30-day trial to try out the service before paying anything.

Aereo had initially stated earlier in the year that it would aggressively expand to 22 markets across the country in 2013, yet Chicago is only the third of those so far and it will go live in September. The likelihood that a further 19 will go live by the end of the year seems a bit far-fetched at this point, though Kanojia has hinted more announcements are looming.