Should you link all your sites together?

Linking between a large number of domains in one “network”?
Im planning to start building a website network that will contain about 100 websites, each with a different domain ([STATE][ONLINE][KEYWORD].com without brackets, for almost every state in the US.) What would be the best way to link between all these sites?

 

My answer to this :

I would not link the sites together unless they were all on separate servers or at least different IPs. I have some experience with this; a few years ago, my client wanted visitors to see how many sites he had and to be able to get from one to another easily. I conceded and all the sites were linked together. A few months later, the sites started dramatically dropping in the ranks. I think the linking was mostly to blame.