When a car going uphill on a one lane road comes across another vehicle coming downhill who should back up?

When a car going uphill encounters another vehicle coming downhill on a one-lane road, the vehicle going downhill should typically back up. This is because the uphill vehicle has the right of way, as it is generally more difficult for it to reverse on an incline. However, the decision may also depend on the specific road conditions and any designated pull-off areas. Ultimately, both drivers should communicate and cooperate to safely resolve the situation.