here's the situation:

This company offers local home services (construction...), but also fabricates many custom items that can be shipped nationally, and even internationally.

Since i started working on this website, it has ranked pretty well on alexa global and locally, and i have made many SEO improvements that doubled the visits to the website in 6 months.

The website is listed in many different directories (dmoz & etc...), maps (google maps & etc...), business listing sites (yelp & etc..), trade specific websites (angie's list, houzz & etc...), state specific business listings and etc, there are many links to pictures displayed on the website, links to the website itself, i have a google analytics and webmaster tools account, with sitemaps, newsletters, facebook page.... the list goes on and on. All of which have been working pretty well locally.

We have had some success with doing business in other states and even other countries, but it is still a pretty small percentage of the market.

I also advertise on google adwords locally, and since this would be the obvious answer, my question is:

Without paid advertisement, how can i improve the visibility of this local business website nationally to attract customers in all US States?