if you live in eastern wi you ll want to take i-94 into chicago. then take i-55 to st. louis then i-44 into oklahoma city. then take i-40 across to barstow, ca. if you are going to southern cal you ll take i-15 south into san bernardino. if you are going to bakersfield or south central, ca take ca-58 through tehachapi and on into bakersfield. from there you have good access to the san Joaquin valley. to go to san diego take i-40 to flagstaff and i-17 south into phoenix. you can take i-10 west from there. once you leave the phoeix metro area there will be a highway that you can take to get to i-8 (it will be well marked) and then you can take i-8 into SD. to get to the bay area or parts north of it the quickest route will have you take i-80 from chicago into california. you will have to go over some mountain passes on 3 routes too. if you livein central wi get to i 39 and take it south to i 80 or i 55. from western wi take i-94 west to st. paul then go south on i-35 to i-80 or i-40.
Depends on where in WI you are. However, regardless of where your at, you ll want to get to Oklahoma City. From there catch the I-40 West right into SoCal.