What is significant about the location of California and Ontario of Canada?

What similarities do you see about their locations?

They possess massive populations, but are not very large in total area.

Yes -- but the question asks about locations, not populations. Ontario is the second largest province in area; California is the third largest state in area.

Keep reading.

I don't know. My textbook doesn't state any other information.

Look at a map.

What type of map?

The accesses to the ocean, as California is located along the coast and Ontario is located along the Hudson Bay, is what is significant about them.

*about their location.

You've got it! A correction, though: Ontario's main connection to the ocean is via the Great Lakes and St. Lawrence River. Together, the lakes and river form the St. Lawrence Seaway.

My answer: The accesses to the ocean, as California is located along the coast and Ontario is located along the the Great Lakes and the St. Lawrence River , is what is significant about their locations.