I think that in this passage the phrase "pack through" means carrying one's belongings on saddle packs on the horses and leaving the wagons (covered wagons?) behind to travel faster to get to the California gold fields sooner. Mr Johnson decided not to travel this way and instead harnessed his horse to the Frink's wagon and they continued as before. The following excerpt intimates what "pack through" means without actually saying it in those many words. "<span>Mr. Wand and his company have left their wagons here and made pack-saddles, intending to pack their clothing, blankets, provisions, and cooking utensils on their animals, in order to travel faster".</span>
