The magnitude of the region which US occupies is 9,826,675 km2.
We don't use unit kilometer here because the unit can be used only when we consider length of boundaries, length of roads etc.
The US Interstate Highway System alone has about 76,788 km of roadway (2012). There are many, many more km of smaller roadways.
A road
4.4 billion kilometers is 4,400 million kilometers.
1,335,470 kilometers
228.5 million km
2,000 meters=2 kilometers
4300 kilometers or 2671.90 miles.
1406km by road.
163km by road.
About 1345
776.9km by road.
About 15km by road.
415km by road.
4331km by road.
About 28km by road.
1240km by road.
About 206km by road.
116km by road.