Decidious pond cypress or evergreen Texas mountain laurel might work and fit that space, though Pond cypress can be hit or miss that far west. 'Debonair' is grafted onto bald cypress rootstock and may be a bit more reliable, but is hard to find. 'Blue Ice' Arizona cypress is another narrow cultivar that might work.

If privacy is the main reason you might consider tall growing evergreen shrubs. These often become tree-like with age. Make sure to plant these so they stay on your side of the property line as they mature. Your neighbor has the legal right to cut anything that hangs over onto his/her property.

Cherry Laurel (Prunus caroliniana) is a tree, growing 25-30 ft tall by 20 ft. wide. However it also does well with pruning. It has white flowers in the spring.

Flowering Pomegranate (Punica granatum) grows 12 to 15 ft. tall and just as wide. Bright orange often double flowers in late spring to early summer.

Burford Holly (Ilex cornuta "burfordii") grows 12-15 ft. tall and 8-10 wide, though some say it can get twice that tall. The dwarf form only gets about 6-8 ft tall.

Yaupon Holly (Ilex vomitoria) grows anywhere from 12-45 ft. tall, but most often to 25 ft. It produces fruit on female plants that lasts into the winter. There are very upright varieties such as "Will Flemming". Leaves are small and dark green and not sharp pointed.

Japanese Yew (Podocarpus macrophylla) is slow growing to 10-12 ft. but only 2-3 ft. wide. There are also weeping cultivars.

Thanks! We are planning to work with the neighbor, as he wants a tree line there too :)

This month's Texas Gardener has an article on smallish trees. They cover Crapemyrtrtles, American smoke tree, Redbud, Desert willow, Texas mountain laurel, Fringe tree, and Palo verde. Don't know if all are suited for your area or space, but the pictures are really pretty.

Lisa