This would all depend on which route you would take to get to Rockford. There are several methods, but the shortest route is taking I35, merging on to I80, and going on to I88. If you choose this way then your halfway point will be Newton, Iowa. From Kansas City to Newton takes 4 hours and from Newton to Rockford takes about 4 hours as well, making the total trip and 8 hour ride by car. For exact directions and other routes for this trip you can refer to Google Maps or MapQuest.
On the route recommended by Google maps it is Milwaukee, but that route goes through the centre of Milwaukee and looks like the worst way to go.
Liberal Kansas is close to the halfway point.
The halfway point between Chicago, Illinois and St. Louis, Missouri is McLean, Illinois according to MeetWays.com.
The exact halfway point is the corner of Ecorse Road and Middlebelt, but that is on a straight line between Wyandotte and Canton.
Concordia, Kansas is the city that is halfway.
According to MeetWays, halfway between Cheyenne, Wyoming and Wichita, Kansas would be a point near Brewster, Kansas on I70.
Kansas
Kansas
If you take I-35 South to Oklahoma City, then the HE Bailey Turnpike to Lawton that is about halfway - it is about 835 miles from KC to Houston and Lawton is halfway on that route. You can also take I-35 to Dallas and going that way Ardmore, OK is about half way - maybe a few miles short of halfway.
maps.google.com Kansas City, Kansas or Wichita, Kansas
What city is Halfway between Goodland, Kansas and Ontario, Canada
A city that is approximately halfway between Calgary, AB and Chicago, IL is Bismarck, ND. It lies about 1,350 kilometers from each city.
The halfway point between Melbourne and London is Akyab, Myanmar.