In general, the closer the web servers are (geographically) to the site visitors, the quicker the pages will load because the greater distance between the web servers and the site visitors often results in more nodes for data to pass through.
With that being said, if your website mainly targets North American users, it is a good idea to find a web hosting company located in either USA or Canada. Also, register a specific domain extension (ie. .us for USA, .ca for Canada) so that search engines can rank your website in a better position based on your geographical setting.
