Illinois operates on Central Standard Time (CST) during winter months, which is 6 hours behind Coordinated Universal Time (UTC-6). During daylight saving time, observed from the second Sunday in March to the first Sunday in November, Illinois switches to Central Daylight Time (CDT), which is UTC-5.
All of Illinois follows the same time zone. Major cities including Chicago, Aurora, Naperville, Joliet, and Rockford all observe Central Time. This makes scheduling across Illinois straightforward, as there's no time difference within the state.
Illinois is home to Chicago, one of the world's major financial centers. When it's 9 AM in Chicago, it's 10 AM in New York and 7 AM in Los Angeles. The Chicago Mercantile Exchange opens at 8:30 AM local time, setting the tone for US futures markets.