What are some reasons to considers san francisco and hong kong as part of the same region

The reasons to consider San Francisco and Hong Kong as part of a same region are:

- Location;

Both cities are coastal cities, and they are connected with the waters of the Pacific Ocean, San Francisco directly, while Hong Kong through the waters of the South China Sea. Both of them belong to the North Pacific region.

- Economy;

Since they are coastal cities, and have well developed ports, big portion of the economy of the cities is reliant on the trade, and most of the trade goes through the waters of the North Pacific, both for export and import. So both of them are part of the North Pacific economic zone.