Niche Site in Google.ca Vs Google.com

[Sunny91]

Hi, I'm in Canada and confused about targeting and searches.

I can only see google.ca so should i be researching local searches and building a niche site with a .ca domain??

How can i target the US?
-webmasters -set site to target US?
-Research using local searches for US
-Buy a .com domain?

Can anyone clear this up???