The distance traveled from Durango towards Broomfield on US-160 is 200 kilometers. This unit of measurement is standard for distances in most countries outside the United States.
If you drove your car 200 kilometers on US-160 from Durango towards Broomfield, then the distance you traveled is 200 kilometers.
The unit of distance you are using is kilometers (km).
When calculating average speed, you would take the total distance of travel (which is 200 km in this case) and divide it by the total time taken to cover that distance.