So, if I read this correctly you want a tree that will go up to block the afternoon sun but not grow too far out so that it will not go over the house or property line.

There are a large number of evergreens that would fill the bill here. You will want either one that is full enough to block the sun or a group that together would provide the blocking.

For a single specimen planting I would suggest Thuja plicata, the Western Red Cedar. http://en.wikipedia.org/wiki/Thuja_plicata
This tree will grow rapidly enough to provide a quick screen but will not spread or overhang beyond the area you have. Since this tree has a very large natural range it will be important to get one that is cold hardy in your area. "Green Giant" is a common named variety.

Another good candidate for a single specimen would be a Sierra Redwood Sequoiadendron giganteum. http://en.wikipedia.org/wiki/Sequoiadendron_giganteum
Although this tree will grow to be the largest tree species in the world, in our lifetimes it will not get that big. It is a fast growing tree that will screen quickly.

I would avoid a Blue Spruce. Even though it is my state tree, I do not like it. They look good in youth but get open and scraggy as they age.

For a group planting, the White Fir would be a good choice. Abies concolor. http://en.wikipedia.org/wiki/Abies_concolor
These grow reasonably rapidly but are not super fast.

For deciduous trees you could choose the Upright English Oak, Quercus robur fastigiata. This tree will grow rapidly and eventually give a broad teardrop shape. For quicker cover, you probably would want to plant three is a triangle in the 25 feet you have. The standard species of the English oak would also be good but may spread too far and need to be trimmed back. They do have the advantage of branching lower than most oaks, not too low to walk under, and the foliage is dense and dark green. http://en.wikipedia.org/wiki/Quercus_robur

You may also consider the Bur Oak Quercus macrocarpa. It also has the advantage of quick growth. Its crown is a little less dense and more open than the English Oak. http://en.wikipedia.org/wiki/Quercus_macrocarpa

Red Oak and Scarlet Oak are also good choices. http://en.wikipedia.org/wiki/Quercus_rubra
http://en.wikipedia.org/wiki/Quercus_coccinea
I have not had much personal experience with these as the Red Oak group will not grow in my area. The soil is too alkali.

There are some maples that would work, but I have issues with maple roots being so shallow. However, you may want to consider the Hedge Maple Acer campestre. http://en.wikipedia.org/wiki/Acer_campestre
This is a well behaved maple of medium height. It is not one of the skyline dominating maples but will also not out grow the space. Being a maple it will grow relatively quickly.

One of my favorites, and one that deserves to be planted more is the Osage Orange/Hedge Apple. http://en.wikipedia.org/wiki/Maclura_pomifera. This is a tree of medium size with a dark, glossy green foliage. The general outline is a short trunked, rounded shape. The roots are very deep and will not compete with the grass or other plants grown under it. The young branches to have thorns which fall as the branch ages. This tree would look good as either a specimen or as a group planting. I have a seedling that has put on 5 feet this year. The Osage Orange has a fruit the size of a softball on the female trees. Some object to a fruit of any kind. but these are large enough to make removal in the fall easy. They will not hide in your plantings or get smashed underfoot. The fruits are only on female trees. There are some grafted, guaranteed male varieties available. There are few pests associated with this tree. The picture is an Osage Orange in fall colors

Well, fastigiate or columnar are terms you want to look for in deciduous trees. The problem is that with a 25 foot space, a tree that doesn't stick outside that can have a canopy at most 25 feet wide.

Which means it can only stick out about 12 feet from the trunk. That's not far.

All this in a tree you want to get tall enough to cast substantial shade in the evening. At least with evening over afternoon it doesn't have to be markedly tall.

I wonder about a fastigiate European hornbeam?

Here is a link that might be useful: Fastigiate European Hornbeam

if you dont plant on growing any foo foo plants below.. look into the maple at the link

ken

Here is a link that might be useful: link

Great responses. I have looked at them all and am going to show the wife as soon as I get a few more to look at.

You guys rock!