(Many entries are extended quotes from other sources)
The big change in the milling industry came in the 1780s with the ingenious ideas of Oliver Evans (1755-1819) from Delaware.
In the summer of 1783 he began working in his ideas for a mill elevator. ... The elevator was an endless band with wooden or sheet metal buckets or cups spaced about 12 inches apart on a belt moving over two pulleys. The top pulley was fixed to the upper floor and the lower one to the basement floor. It was all enclosed to protect the moving belt and ground grain.
This elevator could elevate continouously, and thus lift three hundred bushels of grain or flour per hour. The old method was to hoist it up a tub full at a time, which was the sole work of two men.
Oliver Evans...eliminate[d] forever "the bag and shoulder boys" working in the mills of the time. Evans' "improvements" as he called them, consisted the elevator, the conveyor, the hopper boy, the drill, and the descender. Evans' elevator for unloading ships was described clearly in his book, but its construction did not appear in use until Joseph Dart of Buffalo, New York, in 1843 resurrected the idea from "The Young Mill-Wright and Miller's Guide."
By the end of September 1783, he had [also] perfected the principle for his hopper-boy. The hoppper-boy was a large revolving rake some twenty feet long, adjustable on a vertical shaft by means of a cord and a balance weight. It spead the ground flour after it was ground evenly on the upper floor (called the meal loft), gradually drying it of its mosture so it could be properly sifted. As the rake revolved in a circle on the floor, flour was delivered from a chute at the outer curcumference. Because of the angle of the sweeps on the bottom of the rake, the flour was gradually turned over and over as it moved towards the center. The hopper-boy guided it to a chute leading to the bolting hopper.
The old method was for a boy (called the hopper-boy) to dump the flour on the floor and rake it back and forth with a rake to reduce its heat and moisture so it would not clog in the bolting screens. Then the cooled flour would have to be gathered up and carried to the bolter. Evans' new mechanical hopper-boy fit into his idea to construct a flour mill which could manufacture flour without intensive use of manual labor. The problem was no one paid any serious attention to his claims.
Evans was not trained as a miller or millwright. He had been apprenticed to a wheelwright at the age of 14. Yet Evans when he was 22 developed machines for the manufacture of wool carding teeth and hand carders.
Oliver Evans' two brothers...wanted to build a mill. Since Oliver was mechanically inclined, they asked him to design and install the milling machinery. ...his two elder brothers, John and Theophilus, engaged him to build and equip a grist mill with his improved machinery, on the Faulkland Road where it crossed over Red Clay Creek about two miles from Newport, Delaware. This mill was completed in September of 1785.
At this time Evans also completed his invention of the conveyor, the drill and the descender. [With his mill elevator and hopper-boy,] these five original inventions of Oliver Evans were applied to his idea of an automated milling process. Evans had patented his inventions, then two years later undertook to charge fees on installation of one or all his inventions in mills.
His 1795 publication of "The Young Mill-Wright's and Miller's Guide"...details and describes the construction of devices to overcome the heavy labor in the flour trade and reduce the manpower needs. This book is the first practical technical manual for the milling trade. And, this in many ways was the first how-to book on any trade subject. As it went through its 15 editions until 1860, other technical manuals written for other trades began to appear.
Oliver Evans in his travels around the country side was also trying to locate an interested party in his milling improvements. Finally while traveling in Maryland, he contacted Jonathan Ellicott of Patpsco, Maryland. The Brandywine millers were in particular opposition to Oliver Evans improvements until later when it was used in several mills around them. Jonathan Ellicott and his brothers were the largest mill owners and farmers in the state of Maryland at this time. The Ellicotts owned several large flour mills on the Patapsco River near Baltimore.
Buffalo was the choke point on the route of western grain to the east coast and beyond, for the simple reason that the ships used on the Great Lakes were too big for the Erie Canal. Lake ships had to unload in Buffalo, where smaller canal boats took on grain or flour and hauled it farther eastward.
Along the Buffalo wharves loose grain was scooped into baskets and hauled from lake boats onto the wharves by block and tackle. Sacks of grain, and barrels and casks of flour, were also laboriously removed by human muscle. With luck, the cargo could be transferred to a waiting canal boat immediately. Usually, however, the foodstuffs had to be stored in a warehouse for a time.
This system was tolerable for relatively small amounts of grain, but by the late 1830s, when Buffalo began receiving grain from Michigan and Illinois, it was clear that congestion on the docks and the sheer volume of grain would overwhelm the harbor's ability to handle it.
From Tim Tielman's "Buffalo's unusual claim to architectural fame" webpage (emphasis added)
It was Buffalo entrepreneur Joseph Dart...and engineer Robert Dunbar who applied the new technology of the age to the handling of grain. Dart and Dunbar provided the third element necessary together with motorized lake and rail transportation that brought the age-old grain industry into symmetry with vastly expanded scale of modern life.
In 1842, the two men undertook to erect the 50 by 100 foot Dart Elevator...the first steam-powered grain elevator... By means of a steam-powered vertical conveyer belt made of leather or canvas and equipped with buckets, Dart could unload grain directly from the hulls of a lake vessel moored alongside his storage elevator.
Dart and Dunbar owed a serious debt in their invention to miller Oliver Evans, who earlier had devised a similar conveyer system to handle flour and grain in his milling operation in Philadelphia.
Buffalo entrepreneur Joseph Dart (1799-1879)...had come to Buffalo from his native Connecticut in 1821 and set himself up in the hat and fur business... As the grain trade began to develop in Buffalo after the opening of the Erie Canal, he turned his sights on this growing industry.
Born in Scotland in 1812, Robert Dunbar arrived in Buffalo in 1834, after having studied mechanical engineering in Canada. Dunbar became associated with Dart in his grain elevator enterprise after having erected in nearby Black Rock at least one water-powered flour mill that utilized a new mechanized system for handling grain and flour.
At the time of his death in 1890, Dunbar was eulogized as "the father of the great grain elevator system." His inventions had made possible "all the present improvements of elevators," proclaimed the Buffalo Commercial Advertiser. In addition to the Dart Elevator, Dunbar designed nearly all of the elevators that by the 1880s crowded together along the shores of the Buffalo River. The taciturn Dunbar...enjoyed an international reputation for his remarkable accomplishments in Buffalo. Jobs for constructing elevators came to him from as far away as Odessa, Liverpool, and elsewhere in Europe and Canada.
...By the late 1830s, when Buffalo began receiving grain from Michigan and Illinois, it was clear that congestion on the docks and the sheer volume of grain would overwhelm the harbor's ability to handle it.
Pondering the problem, businessman Joseph Dart hit on the idea of adapting a system of belts and with attached buckets to scoop out the grain. Dart had seen such a system used to move grain around internally around the Ellicott grain mill in Maryland.
In the fall of 1842, Dart arranged a series of buckets 28 inches apart on a leather belt and mounted the belt on a contraption which could be pulled out of his warehouse and into the hold of a ship. The contraption came to be known as a marine leg.
Dart quickly refined the system until the buckets were 16 inches apart and his elevating system could handle 2,000 bushels an hour - an amount that formerly took a full gang of men, working in ideal weather, a full day to unload and store.
Text & photo from Tim Tielman's "Buffalo's unusual claim to architectural fame" webpage (emphasis added)
After 1846, when Dart expanded his elevator - a term now describing his grain warehouse - other businessmen followed. Seven elevators were built in two years. There was a lull until 1861...
From Tim Tielman's "Buffalo's unusual claim to architectural fame" webpage (emphasis added)
The Washington Avenue elevator of the Grand Point Storage Company, Philadelphia, built by George H. Johnson, started in 1859 and completed in 1866. The method was slow to catch on... (From Great Northern Grain Elevator webpage of the History of Buffalo's Grain Elevators website.
The average lifespan of a grain elevator was 12-15 years because of fire and explosion. From Reyner Banham's 1986 A Concrete Atlantis, p. 113m.