It was a complete fantasy, of course. Even the Pearl Harbor raid was the end of the logistical reach of the Imperial Japanese Navy. But that didn't stop newspapers from boosting circulation by convincing American readers that this was a potential outcome.
That's what this page from a 1937 issue of the Los Angeles Examiner is after. So the writers and artists described this fanciful two-pronged invasion of the USA. The first came from an assault on Hawaii, followed by a naval attack on southern California. At the same time, Japan seized southern Alaska and used it as air bases for raids against the Pacific Northwest. Rebecca Onion writes for Slate:
Insets illustrated how Los Angeles could be cut off from the rest of the country with strategic bombing of mountain passes and how its key utilities—water supply and electricity—could be easily controlled by an invading army.
The Examiner thought the main thrust of a Japanese offensive might come from the north. While "crippling or annihilating" the American fleet at Pearl Harbor would be a key part of the plan, allowing Japan to "speed capital ships that would send 16-inch shells screeching to wreak bloody swaths of terror and destruction at Los Angeles and San Francisco," the southern front would "only be a smoke-screen for a main attack via Alaska and Seattle."
You can view a much larger version of the map at Slate.