It is not necessary to capitalize the word mainland. The sentence is fine with mainland in lower case, while North America is in upper case.

they used bridiges that they could raise and lower.

They are a lot of mechanic schools in the B.C. Lower Mainland area. There are probably about 20 different ones to choose from. But only a few are really good schools.

Way too many.

This was a hurricane in 1964 that was upgraded to a typhoon. It hit western Canada lower mainland (Port Coquitlam).