Burying the "way it's always been"

I have been puzzling over a problem we have in our organization. In fact, things I see have profoundly discourage me. I am becoming sensitive to a lack of coordination and unity. What has been called “silo mentality.” It’s always been here at The Bridge and from what I know of the past, it was infinitely worse. The trick is, how do I bury that behavior merely from within my department? (Doesn't that sound ironic?) My department is supposed to make the entire organization look unified and professional, yet I do not have the staff to accomplish this.

Consequently, certain departments here run as if they were their own insular organization with the approving nod of their executive leader.

So how do I beat this discouragement down and turn it into a problem solved instead? I’m thinking that there is a solution but it’s eluding me.