Highway fence with conifers
My house has the backyard facing a highway; I would like to create a visual barrier that hopefully would work also as a sound barrier, although I'm aware that it may not work very well for that purpose. I would like to use some kind of tall (that reach over 16ft high) but thick trees that, planted side-by-side, would completely -- starting from the ground if possible -- block the view, and that would be green year-round (I live in CT, so I think it needs to be some kind of conifer.) The biggest problem is it's going to be a very long fence and I need it to be cheap, so I'm considering even planting seeds. Any suggestions on kinds of plants, where to buy seeds or small trees cheap? Thanks.