What is the importance of where the domains are hosted?

[James]

Most of my domains are co.uk
The content is more appropriate for U.S audience
They are hosted in the UK.

How can the above situation effect my daily visitor count please?

Most of the domains can be found on google.com, but I am not in the U.S and so not know if what I am looking at is what a U.S surfer looks at. I am thinking perhaps if I moved to a U.S host my traffic would increase, but I cannot work out how all the components of this topic effects traffic.

[tedster]

There are at least two major factors involved when search engines serve geo-located results, and you've mentioned both. One is whether there is a country specific domain (.co.uk as you mention) and the other is the location of the hosting service. Other factors may also come into play (and in the future, these may be bigger) including a physical address and phone number in the footer, monetary denominations used, and even the possibility of (in your case) US or UK spelling.

I've read reports of experiments with hosting a .co.uk in the US to get better US traffic. Mixed results, and I don't feel that anything I've read about really isolated the server location factor all on its own. Also, a .co.uk has got to be a bit of a trump card for the present, I'd think, though certainly it's POSSIBLE to rank well from any tld - especially when the countries involved share a common language (sort of).

You can experiment by surfing through a public proxy server and seeing how/if the search results shift. You can find proxy services through a search engine.

Also, note this similar thread:
[webmasterworld.com...]

[James]

Well just to follow up on this. I moved to the U.S for hosting, and have at the moment a 100% increase in revenue, Yahoo and MSN spidering gone mad, and generally can see a positive result by doing the move.