* The roads are not straight. The route between Milwaukee and Grand Rapids follows several state highways, which are not always straight. This adds extra distance to the trip.
* The speed limit is not always the same. The speed limit on some parts of the route is lower than on others. This means you have to drive slower for some stretches of the trip.
* There are traffic lights and intersections. You have to stop for traffic lights and intersections, which adds time to the trip.
* There is traffic congestion. Traffic congestion is common on some parts of the route, especially during rush hour. This can slow down your progress.
* You may need to stop for gas or food. You may need to stop for gas or food during the trip, which will add time.
All of these factors add up to make the drive from Milwaukee to Grand Rapids take almost four hours.