To reach Yukon and Alaska by road, travellers must drive through British Columbia. Most RVers take the Alaska Highway northward and the Cassiar Highway on their return south.
The Alaska Highway is a major route. It is well-maintained
The Cassiar is more remote with fewer services. South of Bell II it is a good highway. North of Bell II it is rougher and narrower.
There is not much difference in the driving distance. The Cassiar route from Prince George to Whitehorse is only 210 km (130 miles) shorter than the Alaska Highway route from Prince George to Whitehorse.