Dutch-American Barns:
Known for their broad gable roofs extending low to the ground; usually two gambrel roofs, used to hang carcasses for butchering (gambrel is derived from the bent part of a horse's leg known as the hock or the gambrel). It had centered doors for wagon entry, generally to transport hay, and often a set on opposite sides. Horizontal siding was generally wide and untapered clapboard, affixed in overlapping or board & batten style. These structures were known for their functionality and simple detail with heavy structural interior - swingle and support beams (mortised, tenoned and pegged) arranged in H-shape with purlins and columned aisles. Beams were usually adzed. Characteristic of this type of barn, their cross beams were often rounded at the ends to form "tongues." They were common in New York and New Jersey, reaching into Pennsylvania. Generally speaking, they were erected circa 1600s through 1850s and reveal obvious European influence. Interestingly, there were no such barns in the Netherlands during this time period - the Dutch adapted these features while here in early America!
Bank Barns:
Also known as Sweitzers, these barns got their name simply because they were built into a hill. The biggest reason for this was to allow ground entrance on two floors. Generally animals were housed on the lower level and the upper lever was used as a threshing floor and for storage. Hay to feed the animals would be dropped to the lower level through openings in the floor. Large upper level doors allowed wagon access. Generally they were built on the southern side so the animals would have maximum sun and for protection from the elements. The second floor would generally cantilever over the first for additional animal protection from the elements. Roofs were of varied pitches, and sidings ran either horizontal or vertical. These structures were common to Pennsylvania Country. They peeked popularity in late eighteenth century. Initially they were smaller structures, but as their popularity grew, they became magnificent, often with three or four dry cellars for storage, two or three threshing areas and two granaries situated in the corners of the over hang. They could fit up to 4 dozen animals comfortably, with food enough to feed them all, too.

Crib Barns:
A crib to a barn is simply an enclosed storage place. A crib barn was a rather small structure presenting an enclosed area used for storage, generally for things such as corn or hay, and a simple human-size entranceway. As corn was a major importance to a farmer, the barn held much significance. For this reason, they evolved from single cribs to double, quadruple and more. Eventually they transformed into fully functional barns with threshing in the hallway areas in between cribs and animal quarters. They were often erected and occupied before a main house was built. Some were made of stone, but most were of logs. Roofs were thatched, shingled and shaked. Eventually they developed into the slant-walled crib barns, whose function was exclusive. Common in South and Southeast, these barns were built during a large portion of American history.

Tobacco Barns:
Tobacco was generally a small crop for farmers in Early America. At first, tobacco (which must be dried from the 90% water content at time of picking to about a 10% or less water content) was dried, or cured, by hanging leaves on nails in hay barns. But as demand grew, fascinating barns were designed. The challenge - and apparently there was a certain competitiveness to tobacco barn ownership - was to make an art out of drying, generally using some form of fire or smoking. Ventilation was key. Many methods were derived over the years: multiple vents hinged at the top were placed strategically all over the sides; every other board of vertical clapboard siding was propped outwardly to create flow of air; large doors were, instead of hinged to swing outward, put on tracks so they can be rolled open and shut. Tobacco barns could be found up and down the East Coast, and many can still be found today. They were generally unpainted, until red with white trim paint became popular in the North East.

Round Barns:
Many believe that the appearance of the round barn was brought on by religion - farmers were the most respected members of religious sects in Early America, and these sects were inclined to relish emblems. Since the circle was so common in their lives (praying and other community circles, in their drawings, in their other possessions like rugs, etc.) the circle barn, it is believed, was a consequence. They came about relatively late in early American history, circa 1875s and only remained in construction through early nineteenth century. The circular interior - the Utopian shape - was found to be more efficient: easy work flow, less restrictive, superior use of space, less material needed to build one, self-supporting roof. Farmers could actually drive their wagon around the interior perimeter, completing work as they went. Animals could even get exercise on a type of circular run, similar to what we see at modern horse farms. The early versions were actually multi-sided, but eventually they became perfectly round. Their exterior ranged from vertical or horizontal wood to glazed or stone. They can be found up and down the East Coast.

Summary:
Although there are countless other types, most other barns were generally derived from one of these styles. Often you can find one or more styles in one barn. It should be noted that the early American farmer’s barn design was influenced only by the building’s purpose and reason it was being created.
Efficacy was vital. Early American farmers did not have time or money for waste and poor judgment. Their barn was their life line.
Historical barns that are still standing often have several additions, designed with different styles but all for the same purpose – function and need.
This symbol signifies a reclaimed material , which meets "green building" standards.
If you see it, than that material is architecturally sustainable!