During the Gilded Age, Cooper became an ardent critic of the gold standard and the debt-based monetary system of bank currency, advocating instead for government-issued banknotes.

[1][2] He worked as a coachmaker's apprentice, cabinet maker, hatmaker, brewer and grocer,[1][3] and was throughout a tinkerer: he developed a cloth-shearing machine which he attempted to sell, as well as an endless chain he intended to be used to pull barges and boats on the newly completed Erie Canal (which was routed west to east across upper New York State from Lake Erie to the upper Hudson River) which its chief supporter, the Governor of New York, De Witt Clinton approved of, but which Cooper was unable to sell.

[1] In 1821, Cooper purchased a glue factory on Sunfish Pond[4] on east side Manhattan Island for $2,000 at Kips Bay, where he had access to raw materials from the nearby slaughterhouses, and ran it as a successful business for many years,[5] producing a profit of $10,000 (equivalent to roughly $200,000 in 21st century value today) within 2 years, developing new ways to produce glues and cements, gelatin, isinglass and other products, and becoming the city's premier provider to tanners (leather), manufacturers of paints, and dry-goods merchants.

Seeing the Baltimore and Ohio Railroad as a natural market for iron rails to be made from his ore, he founded the Canton Iron Works in Baltimore, and when the railroad developed technical problems, he put together the Tom Thumb steam locomotive for them in 1829 from various old parts, including musket barrels, and some small-scale steam engines he had fiddled with back in New York.

[7] Cooper later moved the mill to Trenton, New Jersey, on the Delaware River to be closer to the sources of the raw materials the works needed.

His son and son-in-law, Edward Cooper and Abram S. Hewitt, later expanded the Trenton facility into a giant complex employing 2,000 people, in which iron was taken from raw material to finished product.

He dressed in simple, plain clothes, and limited his household to only two servants; when his wife bought an expensive and elaborate carriage, he returned it for a more sedate and cheaper one.

[12] In 1854, Cooper was one of five men who met at the house of Cyrus West Field in Gramercy Park to form the New York, Newfoundland and London Telegraph Company, and, in 1855, the American Telegraph Company, which bought up competitors and established extensive control over the expanding American network[14] on the Atlantic Coast and in some Gulf coast states.

Prior to the Civil War, Cooper was active in the anti-slavery movement and promoted the application of Christian concepts to solve social injustice.

This organization, whose members included William E. Dodge and Henry Ward Beecher, was dedicated to the protection and elevation of Native Americans in the United States and the elimination of warfare in the western territories.

[20][21] Edward served as Mayor of New York City, as would the husband of Sarah Amelia, Abram S. Hewitt, a man also heavily involved in inventions and industrialization.

[22] Cooper was a Unitarian who regularly attended the services of Henry Whitney Bellows at the Church of All Souls (New York),[23] and his views were Universalistic and non-sectarian.

In 1853, he broke ground for The Cooper Union for the Advancement of Science and Art, a private college in New York, completing the building in 1859 at the cost of $600,000.

Cooper started a Women's School of Design, which offered daytime courses in engraving, lithography, painting on china and drawing.

[29] In 1851, Cooper was one of the founders of Children's Village, originally an orphanage called "New York Juvenile Asylum", one of the oldest non-profit organizations in the United States.