He was an associate of Bishop William White and others in the formation of the first American Sunday School Society.
While the War of 1812–14 was kindling he wrote much on political subjects, and in 1814 the Olive Branch appeared, in which he attempted to harmonize the contending parties in the United States. It passed through ten editions.
In 1818 he published “Vindicia Hibernicæ,” which was a refutation of charges made against the Catholics of Ireland of butchering Protestants in the insurrection of 1640.
In 1820 he published “The New Olive Branch,” which was in favor of protection to American industry; and two years later his “Essays on Political Economy,” were also published in favor of protection. These publications were widely circulated.
In 1830, under the title of “Miscellaneous Essays,” Carey republished selections from his writings. There are fifty-eight papers, essays, and longer compositions, and two hundred pieces collected under the heading of “Light Reading.”
Carey also advocated the system of internal improvements which led to the construction of the great canal system in Pennsylvania.
He was active in promoting education, and in forming associations for the relief of those unable to help themselves.
As Matthew Carey advanced in years, he acquired a fair amount of wealth, and in consequence of ease and comfortable environment, he became a prolific writer, but always on subjects which were solid. He gave no time to the elegancies of literature or fiction.
In this field of literature he was succeeded by his son Henry Charles Carey, who became well known for his robust works on political economy.
In 1833–34 Matthew Carey contributed his autobiography to the New England Magazine.