When entering an interstate highway, you should:
Stop, check for cars, and enter when safe.
Check for cars and reduce your speed to 25 mph before entering the traffic lane.
Check for cars, increase your speed to match the flow of traffic, and merge when the way is clear.
Rather than stopping (as you would when entering other roads), you must use the merging or acceleration lane to speed up and smoothly merge with fast-moving traffic already on the interstate.