Question
I live in southwestern Ohio.  I have spruce trees that are planted right next to each other, and had to cut one of them down.  Now that the one is down, the trees on either side have dead limbs where the old tree used to be.  Is this due to the old tree blocking the sun to those limbs?  If I cut off the dead limbs on the live trees, will new ones grow in their place?  HOw long should I expect that growth to take?

Answer
Yes the dead limbs are from the shading --this is a natural form of self pruning. Unfortunately conifers will not resprout new limbs on the lower trunk. You did not say how large the tree were but I assume they are more then seedlings. What can be done to even up the appearance of the tree is prune some of the branches off the other side of the tree. This will not effect the health of the tree but is fro looks only. Make sure you leave more than 40% of the total tree height in foliage (crown) if you do prune some of the branches.