A century ago, the Earth's climate was just emerging from the Little Ice Age. Temperatures were colder, glaciers more advanced. Surprisingly, the Valdez gold rushers may have benefited from the colder climate.
For example, boats arriving before mid-March could drill 18 inch holes through the ice at the head of Port Valdez and tie the steamer's lines to the ice. Then the prospectors simply unloaded their tons of supplies on to the ice. Now, a century later this would be impossible. The head of Port Valdez freezes only sporadically in winter
Because the temperatures remained cooler longer, less snow melted in the mountains and more ice flowed down Valdez Glacier. In 1898, the terminus of Valdez Glacier was only five miles from the shoreline.
Today's, Valdez Glacier Lake did not yet exist. But if you stand on the edge of Valdez Glacier Lake you can look across at the mountainside and see the vegetation marking the old lateral moraine which indicates the height of Valdez Glacier in 1898.
Hauling supplies up the steep terminus was more difficult in 1898 than it would be today, however the cooler temperatures and greater snowfall filled the crevasses and covered the glacial ice for longer periods making the route safer for more days of the year. And, it was certainly much easier for prospectors to haul their supplies on sleds, than to carry them across boulder strewn outwash plains or across summer's swift rivers.
(Read more crossing Valdez Glacier in Margeson's Experiences of Gold Hunters in Alaska and the Lethcoe's Valdez Gold Rush Trails 1898-99. )