If your state issues you two plates, then yes, you will be required to put one on the front and one on the rear of your vehicle. There are a few states, such as Florida, that only issue you one license plate. When only one plate is issued, it is usually required to be placed on the back of your vehicle.
California and New York both require you to have both your front and back license plates, which you are issued by the DMV, to be properly attached to your vehicle or you can be ticketed by law enforcement.
Specifically California Vehicle Code 5200 requires two license plates be attached, one to the front and one to the back of all automobiles and light-duty trucks.
As for New York, NYS DMV states that they have issued you two vehicle plates for your vehicle; you must use both vehicle plates. Put one vehicle plate on the front of the vehicle and one vehicle plate on the back of the vehicle. There are no exemptions to this requirement. They go to say if there is only one location on your vehicle to attach a vehicle plate, contact a parts store to get a device to attach the other vehicle plate to your vehicle.
The NYS Police and other law enforcement agencies recommend that vehicles display two vehicle plates. The two vehicle plates help the police to identify vehicles. The NYS vehicle plates use a reflective material, and the two vehicle plates improve the visibility of vehicles at night
If you use one vehicle plate instead of two vehicle plates in New York, you can receive a fine of $25 to $200 and mandatory surcharges of $50.
The NYS DMV does issue only one vehicle plate for some vehicles. These vehicles include trailers, motorcycles, and the tractor unit of a tractor-trailer.
In Missouri their DMV notes that MO law requires that license plates be securely fastened to a vehicle, and that all parts of the plates be visible and clean for view or inspection by any law enforcement entity. If you have frames around your license plates, the Missouri State Highway Patrol reminds you that the frames must not cover any part of the plates.
If the MO Department of Revenue issues a you, the car owner, two plates then you must place one on the front and one on the back of your vehicle. In this state if you have a trailer or a motorcycle, you will only receive one plate, which must be on the back of your vehicle. If you have a truck licensed in excess of 12,000 pounds, you will only receive one plate, which must be placed on the front of the truck. If you want a second plate, it must be specifically requested. You must place the original plate on the front of your truck and if a second plate is issued, it must be placed on the rear of the truck.
Our research shows that over 30 states require both a front and rear license plate. This includes the states of Massachusetts and Connecticut who have in recent years gone back to requiring 2 plates after previously only requiring 1 plate. Front plates are believed to improve the effectiveness of law enforcement and the new technologies they now use, such as laser guns used to catch speeders.
To find out what your particular state requires regarding the number of license plates that must be attached to a motor vehicle, contact your local Department of Motor Vehicles. This state agency should also be able to advise you as to what the penalty would be if you choose to only drive around with one license tag on the car if two are required.