Most boot makers make hiking boots with one width - striking the middle, according to the last, which may be narrow or wide depending on the preference of the maker. Although it is a little difficult to find a perfect pair of narrow hiking boots, a little research can get you just the right one for your feet.
Few boot makers do make narrow hiking boots. Boot makers such as Italian boot maker, Kayland, makes narrow hiking boots. Models such as the Traction K is medium-heavy backpacking boot which is available in narrow width. Others such as Vasque also make narrow hiking boots. The Vasque Sundowner is a popular hiking/backpacking boot that is also available in the narrow variety.
Narrow hiking boots are available at major hiking/backpacking stores that have a wide array of boots. A good fitting regular hiking boot might also be used with a clever combination of socks and insoles. Some boots have the tendency of fitting to a select group of people with wider feet. For instance, the L.L. Bean's Leather Cresta Hiker and several other hiking boots from Montrail, including the Vercors are also likly to fit well. Thus, there is a limited collection of narrow hiking boots to find from, you can get the best suited pair for you through careful selection.