A winter visit to Mount Rushmore is pretty dramatic. There were no crowds and the weather was very accommodating as it was around zero Celsius, with no wind but no sunshine.
The monument itself may be briefly seen from the highway, but to get the best look you need to park and walk up to the viewing area. You have to pay to park, which is how the National Park’s Service get’s it’s money.
In fact, the highway is constructed so that there is no real place to pull over. You can see a profile view of George Washington from a pull-off on the highway just to the west of the Mount Rushmore site, but that is just a tease of the magnificence of the entire site.