Even though Chicago is the biggest major in-land city in America, its diverse economic sectors allows it maintain its status as a competitive global city. Chicago is the country's main railroad hub. Not only is it paramount to the transportation of goods nationally, but its ability to ensure that not a single industry dominates more than 14% of the city's workforce helps its economic endeavors. Having one of the most active airports in the world and an infrastructure proven to be conducive to a plethora of industries, it makes it an ideal location for companies to plant their headquarters as Exelon, JLL, McDonald's, and Motorola all have done.