What is the age, height, and weight requirement for sitting up front in a car?

Question

What is the legal height, age, and weight requirements for sitting up front in the passenger seat in Michigan?

Answer 1

Michigan State Police state firmly that:

Children must be properly buckled in a car seat or booster seat until they are 8 years old or 4-feet-9-inches tall. Children must ride in a seat until they reach the age requirement or the height requirement, whichever comes first.

The page goes on to recommend that children ride in the rear seat until they're 12.

It also says that the seat belt must be properly adjusted--whether the child is in the front or rear seat.

Incorporating Joe W's comment with a little extra.

If a vehicle has no rear seat or all spaces in the rear seat are occupied by children under 4, a child under 4 can ride in the front seat using a rear-facing child seat but the air bag must be turned off.

Extrapolating from that, I assume if the rear seat is full of children under 4 that a child older than 4 can ride in the front seat in an appropriate child seat or booster seat.