The tulip poplar is a nice tree, taller than wide, but will eventually become taller than you specify.

It is vulnerable to lightning, they say, and tends to self-prune its lower branches, mainly by dropping them in wind, I would think.

We have one in the Southeast side of our garden; it self sowed there years ago and eventually shaded out some pines nearby. It was mowed over innumerable times before its presence was accepted, and didn't seem disturbed at all by that. The ground there seems a bit moister than in other areas of the lot.

Although I was unaware of its "self pruning" tendencies, I had surrounded it with shrubs that make casual perambulations under its branches highly unlikely, and none of its dropped branches have gotten outside of that boundary...the shrubs extend about 15 feet around the tree, but 20 would probably be safer. It is downwind from our house, and I personally wouldn't want our house to be upwind of it, but it does cast solid shade and can grow at a decent rate in a spot that it likes.

The Tulip poplar leaves are irritatingly large, but seem to decompose well. It also forms large green flowers with an orange center, usually not that visible from the curb, which appear to attract hummingbirds (which you will never see unless you plant flowers at your own level, or watch from a high window).

The especially quick-growing strain of white pine developed in the South as a good source of lumber have become popular to plant in hedgerows around here; I shrudder whenever I see them planted like that, because I grew up in a home surrounded by six or seven mature ones that had lost all of their lower branches. We used to worry each time we had a hurricane (this was in Massachusetts) at the thought of one of those giants falling on the house. They never did, and by the grace of God or dumb luck none of their fallen branches ever caused severe damage.

I only mention white pine because, if you are impatient, the new variety should certainly provide you with the shade you desire more quickly than, say, an oak. They should not be planted close to currants or gooseberries because of a lethal disease that can be transmitted to them from those. The needles are a few inches long, and they make an attractive, acid mulch.

If you are in a great hurry for shade and have sufficient moisture, you might consider the willow. It probably grows more rapidly than anything, and will easily root in plain water if you obtain a fresh cutting from new wood. It is a rather short-lived and fragile tree, easily damaged by storms, but the wood is so lightweight that it causes little damage if a branch, or even the whole tree, falls. It makes a pleasant rustling sound in the wind, and has long, little leaves which practically disappear after falling. It is usually as broad as it is high, and may not get as high as you would like.

The Norway maple is a tough, serviceable tree with broad, dark leaves that will eventually cast total shade under itself. It is the epitome of the "shade tree," and what many think of when they think of shade trees. It is hated by lovers of native plants and the ecology, because it is an unyielding foreigner that has little sympathy for the needs of native plants and animals. It effectively kills off everything underneath it unless good open area surrounds it, in which case you might be able to grow non-flowering daylilies and similar items under it. The base will broaden as it grows, and you should expect some root pressure for about five feet around the tree, but probably no further if it has sufficient area providing moisture seepage. It will probably max out at about 50 feet, and tends to be almost as wide as it is tall, but responds well to the removal of its lower branches. It will lose twigs at times in wind, but does not seem as prone as other maples to limb loss. The leaves are more substantial than those of some other maples, but will eventually decompose if composted, and I have often used them after a few seasons in garbage bags as part of the components of "lasagnia gardens." The seeds are the flat "flying" ones that children like to split and stick on their faces, and they will need to be swept if too closed to the driveway.

The oak has a deep tap root which loves to invade water pipes, but does not cause surface root problems. It can produce extremely heavy wood, and is a slow grower. It can totally destroy a house if it falls on one--usually not a concern if you choose the proper variety of oak for your area. Cushioning branches also help to minimize house damage, but many trim their trees too high for this to be a factor. (In my neighborhood, someone lined many of the streets with pin oak, which responds to our humid climate by developing weak roots that allow the heavy tree to fall when fully mature and able to cause real damage). Some varieties have acorns significantly larger than others; all of them will attract squirrels, which will happily take them off of your hands. The loose, long catkins they produce while blooming are another annoyance; but at least oaks don't reseed as readily as most maples.

The leaves of the oak are so tough that they overwinter on the tree, and are still resistant to composting when they finally fall in the spring, unless ground up first. If you like acid-loving plants, though, they make a good mulch for those if first ground up and composted a bit.

I personally would plant a beech tree in front of my home if I had the space; it is a beautifully formed tree with dense, attractive branching which produces tiny nutlets that little creatures enjoy. It appears to be rather slow growing, and has a rounded shape which can be ruined if the lower branches are removed excessively. There is one across the street from us, and we have never seen a leaf from it in our front yard--unlike the leaves of the oaks, which blow over to us all the time. It would perhaps be too wide for you, since it seems to need about a 50 foot space for itself.

If you provide more information as to the amount of space you have available, the drainage, the surrounding plantings, the positioning of your driveway relative to the house, the house and driveway orientation relative to the sun and prevailing wind, others should be able to provide more specific input. Observation of the plantings on your close neighbors' properties can also be helpful.

Most trees can produce a great deal of pollen when mature, so if anyone in your family has pollen allergies you might also want to make that a part of your decisionmaking process, especially if the tree is to be downwind of the house.