Many companies specialize in period-appropriate fences. Suppliers are located coast to coast; some ship nationally. You should, of course, look for your own local sources as well.
Wood fencing is a large category, often coming from companies that also make pergolas, arbors, gates, and gazebos.
Bear Creek Lumber Lumber for fencing in different grades & various cedars plus redwood & fir (posts)
Cedar Rustic Picket, privacy, lattice etc.; also aluminum fences
Cape Cod Fence Classic New England picket fencing (design, sales, installation) since 1956; metal fencing; they will ship
Charles Prowell Woodworks Decorative fences, driveway gates, arbors, lighting columns
Garden Arches Hand-built arbors & trellises with complementary fence options
Garden Structure Plans, kits & info for DIY fences, pergolas, trellises, decks
Museum Resources Materials, design, installation of restoration- and museum-quality fencing: picket, pale (plank), & rail, sawn & riven styles. Knowledge of regional types. White oak, old-growth cypress, white cedar, longleaf pine.
Perfection Fence Picket fences, pergolas, arbors
Peter A. Kirsch-Korff Fine custom wooden fences, privacy screens, arbors, decks, pergolas, gates, tree houses; Los Angeles County only, but website is helpful
Trellis Structures Wood garden structures, fences, gates, custom work
Walpole Outdoors All garden structures including fences, arbors, pergolas, lattice panels
Woodway Products Quality fence components including rails, lattice panels, caps
Metal fences run from simple rail and spike designs, to custom wrought and cast iron. Most of these companies also fabricate driveway gates, balustrades, and grilles.
Big Easy Ironworks New Orleans-style iron fences; informal plantation fencing & wood fence
Bill’s Custom Metal Fabrications (516) 945-4077, Fences, gates, railings, architectural ironwork
Bushere & Son Iron Studio Custom decorative ironwork incl. gates & fence sections
DeAngelis Iron Work Custom metal design, fabrication, restoration
Fence Depot Aluminum, iron, steel fencing & gates
Fence Town Aluminum fences & gates, residential/commercial
Iron Eagle Industries Traditional metal fencing & gates
Iron Fence Shop Iron & aluminum fencing & driveway gates Perfection Fence perfectionfence.com Architectural & ornamental “picket” metal fences
A Rustic Garden Wrought-iron fences & gates, decorative steel entry gates, iron driveway gates, roll-top wire fencing
Old Dutchman Wrought-iron railing, fences, gates in the greater Buffalo, NY, area
Robinson Iron Museum-quality fences, gates, railings in cast & wrought iron & water jet-cut metals
Stewart Iron Works Iron fencing etc.; preservation specialists
White Hart Forge Blacksmith-made custom iron fencing
American Fence and Supply Co. Straight steel & aluminum fencing with factory finish in black, bronze, white, hunter green; split-rail fencing
Hutchison Inc. Ornamental, galvanized wire & double loop fencing, 36–48” high
Specialty suppliers offer old-fashioned rural wire fencing, and even cutout designs suitable for mid-century homes.
Acurio Latticeworks Ornamental PVC panels for special conditions & compatible with MCM houses