I second the suggestion on Ilex crenata--it really looks like boxwood and is easily trimmed. I find it's growth moderate. I have one large specimen and it seems always to need a haircut. There are other species of Ilex (Holly). Some of them native to your area (Ilex vomitoria)--but not sure of its growth rate. Photinia "red tip" grows very fast but I understand they suffer some kind of fungal problems in the South--especially when grown close together. I'm sure there are many possibilities for plants but the ones I have used for formal hedges include azaleas, Photinias, holly, boxwood, and Euonymous japonica.

Research the narrow growing yews. Last year during an extended drought period, I planted a row of two yews and a tree form crape myrtle with that drifting group replanted in an alternating pattern over a narrow 60 foot long area which runs in the space between a chain link fence and a driveway. I do not remember the cultivar name of the Yews, but they are suppossed to grow much more narrow than even the Hick's or the Plum yews grow. We kept them watered regularly and they are still surviving. These yews are evergreens, which are supposed to grow 10 to 12 feet tall, but can be pruned shorter and spread only about a foot or so. Some are in shade and some are in more sun. The Crape Myrtles that are planted amid them will eventually provide for the yews almost constant shade during the Crape myrtle's growing season. The Yews will also receive quite a bit of part-sun in the winter when the tree form Crape myrtles are dormant. The bed is currently mulched with shredded cedar mulch, and is gradually being fill in with flowering ground cover shrubs that should grow at the feet of the Yews and Cm's along with filling in the area of the currently mulched bed. at the end of the chain link fence and still along the driveway I planted an ornamental and narrow growing, pink blooming, Corinthian Peach tree. At its feet I planted some wave patunias on the north side, a dwarf spirea on the south and so for two Dwarf Yaupon holly on the east side of the the tree. Later on I will extend the bed along the driveway and plant a Black Tupelo tree about 20 feet south of the ornamental peach. Since that tree will be in the front yard area I will be planting the tree on the property line along that narrow side of the driveway, and as it grows and spreads, I plan to keep it pruned up to provide enough space under the canopy for pedestrians and traffic flow on the street which is about 15 feet further south running along the front yard curbing. As of now I have not planned anything further to be planted on that side of the driveway between the ornamental peach and the Black gum, Tupelo tree. Over time though I might change my mind.

Pierce, just be aware that you will need a male holly for every 5-7 female plants to get berries. Because you will be planting tightly, you might be able to stretch it to one per 10 females. Most of the male forms I know of are shorter growing than the females, in general. You could get around this by using 1-gallon males and planting in the same hole as the females/'Nellie R.Stevens' as you space them out - they can grow up and be available, but are 'hidden' among the mass of the females. I know 15 gal. 'Nellie R. Stevens' are available, but can't speak as to price. While the 'Nellie R. Stevens' are a good hedge plant, if you wanted to mix in another type of tree, the Thuja 'Emerald Green' (a.k.a. 'Emerald Beauty' or 'Smaragd') is another good hedging plant, growing fairly fast to 12-15', and about 3-5' wide. You can fairly easily find 5 gallon plants, at about 4-6' tall - and pay more for them than 1 gal. - so they might be good where you want immediate height. While running bamboos will provide a solid screen once they are established, they will also RUN!! I have pulled out runners that are up to 8' long, and about 6" deep, in the spring. As long as you mow faithfully, you can keep them in check. However, even asphalt won't stop them from coming up - cement MIGHT! You can buy barriers, but you need to make a 3' deep trench for the barrier to be effective, and even then, you will probably have to watch for escapees over the top. Clumping bamboos are much better behaved, and will expand, but stay where you plant them.

That's what I thought from the title, and even more so after reading the post. Knowing your location could help determine if this is a likely suggestion, if you're unable to tell from comparing pics of the suggested plant to yours and are still investigating.