I realize that Alaska is only the size of Queensland, mate, which makes it moderately sized by Australian standards( and twice the size of Texas and New South Wales), but the state of Alaska as it is is so big that it's unwieldy. For one thing, the capital, Juneau, is stuck in a panhandle made up of fiords like you find in Norway and Western Tasmania and New Zealand and totally detached from the rest of Alaska. It would be like New South Wales including Victoria, South Australia and Tasmania--and having it's capital at Hobart.
Secondly, while Alaska is cold, it's no colder than much of European Russia or Sweden. And it's well watered with plenty of ice and snow. There's as much arable land in Alaska as you find to make up a state the size of Oklahoma. Or Victoria. And because so much of it is so close to the Arctic Circle, that land gets anywhere from 18 to 24 hours of sunlight during much of the growing season. Which means that 60 frost free days is the equivalent of 90 to 120 frost free days in, say, Iowa or Minnesota. That's why it's possible to grow corn and feed hogs up near Fairbanks
Thirdly, unlike Australia, Alaska is broken up by several mountain ranges. So if Alaska were fully settled, you'd have one major center of population in the Panhandle (and a small one, at that, because there is little level land), one around Cook Inlet and the Copper River Basin to the east of Cook Inlet, one in the Tanana Valley around Fairbanks, one around Bristol Bay and the Alaskan Peninsula west of Cook Inlet and the Alaska Range and one around the Sweard Peninsula and the Bering Strait, with much more thinly populated hinterland all around it. It's a bit like Australia itself, actually. Alaska's Top End fully settled would have huge amounts of oil and coal production, but also reindeer ranching, bitter cold though it is. Even moose can be domesticated, it turns out, for milk as well as meat. All Alaska needed was what Australia needed, infrastructure and a lot of immigration at the turn of the 20th Century. Alaska did not get railroads and settlement for a number of reasons, Aussie Hawker. Firstly, the Russians never got settlers into Alaska by the time they sold it to the Americans in 1867. Secondly, as soon as Alaska was sold, the Republican Congress went all Tea Party about it and refused to appropriate a nickel to administer Alaska, claiming that acquiring it in the first place was a waste of money and could the government please sell it back to the Russians? This state of affairs lasted until a bloke named Juneau discovered the first gold in Alaska in 1885, which is how the town of that name got built and how that town became the Territorial and then State Capital. Also as a result of Congress's pique, the US never got around to settling a boundary dispute with British Columbia until 1903.
Between the two, Alaska missed the boom in railway building in the 1880s and 1890s.The Union Pacific almost built a railroad to Alaska as a joint venture with the Canadian Grand Trunk Railroad, being built from Winnipeg to Prince Rupert, but the plan was to actually build the line over the Bering Strait into Siberia and across to European Russia. When Theodore Roosevelt mediated the settlement of the Russo-Japanese War somewhat in Japan's favour, conservatives in Russia got the Russian Government to withdraw approval for the railroad. Then the Cold War intervened--until now President Putin is trying to revive the idea.
And in the US, the Panic of 1907 ended just about all investment in railroad expansion and investors did not distinguish between possibly good projects and bad projects because so many railroad investors had lost their shirts. And railroads had a bad reputation and the public was against the government doing any more to help them. By the time paved roads started being built, the US had a glut of farm products and even though farms were being lost to dust bowl drought, Franklin Roosevelt was not about to open up huge new areas to farming. And by the 1960s, when the demand for farm products was up, the US was starting to see the environmentalists come in claiming that any expansion of farmland or human habitation or human activity at the expense of any wilderness was an unmitigated atrocity. So there you have it. ,