You may find this post useful How to Rank within Country Specific Searches.
If you want to rank high in US you can set the geographic location in your Google Webmaster Tools account

The concept you are referring to is actually a sort of country specific web optimization strategy which involves getting backlinks for websites, coming from IP addresses in the same country or geographical which is the choice among webmasters. Naturally, a lot of US based links will help your site getting better ranks on Google.com portal.

This is the reason why even hosting related issues could have roles to play, back to the example above, it is suggested to use a US based hosting account in order to have better rank on US based Google.