Simplify the following text for a Grade 4 native English-speaking person.
Original: Sandwich is a city in DeKalb , Kendall , and LaSalle counties in the U.S. state of Illinois .
Simplified: Sandwich is a city in the U.S. state of Illinois . The population is 7 , 337 and is in the county 's DeKalb , Kendall and LaSalle .