Where is Rockford (Illinois, USA) located ?

Abilene Adak Akron Albany Albuquerque Alexandria Allentown Amarillo Anaheim Anchorage Ann Arbor Arden-Arcade Arlington Asheville Atlanta Augusta Aurora Aurora Austin Bakersfield Baltimore Baton Rouge Beaumont Berkeley Billings Birmingham Bismarck Boise Boston Bridgeport Brockton Brownsville Buffalo Burbank Cambridge Carson City Cedar Rapids Chandler Charleston Charlotte Charlotte Amalie Chattanooga Chesapeake Cheyenne Chicago Chula Vista Cincinnati Citrus Heights Clearwater Cleveland Colorado Springs Columbia Columbus Compton Concord Corpus Christi Costa Mesa Dallas Daly City Davenport Dayton Denver Des Moines Detroit Diego Garcia Downey Durham El Monte El Paso Elizabeth Erie Escondido Eugene Evansville Fairbanks Fall River Flint Fort Lauderdale Fort Wayne Fort Worth Frankfort Fremont Fresno Fullerton Galveston Garden Grove Garland Gary Glendale Glendale Grand Prairie Grand Rapids Green Bay Greensboro Guam Hampton Harrisburg Hartford Hayward Helena Hialeah Hollywood Hollywood city Honolulu Houston Huntington Beach Huntsville Independence Indianapolis Inglewood Irvine Irving Jackson Jacksonville Jefferson City Jersey City Juneau Kansas City Knoxville Lafayette Lakewood Lancaster Lansing Laredo Las Vegas Lexington-Fayette Lincoln Little Rock Livonia Long Beach Los Angeles Louisville Lowell Lubbock Macon Madison Memphis Mesa Mesquite Metairie Miami Milwaukee Minneapolis Mobile Modesto Montgomery Montpelier Moreno Valley Nashville New Bedford New Haven New Orleans New York Newark Newport News Nome Norfolk Norwalk Oakland Oceanside Oklahoma City Olympia Omaha Ontario Orange Orlando Overland Park Oxnard Paradise Pasadena Pasadena Paterson Pensacola Peoria Philadelphia Phoenix Pierre Pittsburgh Plano Pomona Portland Portsmouth Providence Pueblo Raleigh Rancho Cucamonga Reno Richmond Riverside Roanoke Rochester Rockford Sacramento Saipan Salem Salinas Salt Lake City San Antonio San Bernardino San Buenaventura San Diego San Francisco San Jose Santa Clara Santa Clarita Santa Fe Santa Rosa Savannah Scottsdale Seattle Shreveport Simi Valley Sioux Falls South Bend Spokane Springfield Springfield Springfield St. Louis St. Paul St. Petersburg Stamford Sterling Heights Stockton Sunnyvale Sunrise Manor Syracuse Tacoma Tallahassee Tampa Tempe Thousand Oaks Toledo Topeka Torrance Trenton Tucson Tulsa Unalaska Vallejo Virginia Beach Waco Warren Washington DC Waterbury West Covina Wichita Wichita Falls Winston-Salem Worcester Yonkers Youngstown