He made a fortune in privateering and the Old China Trade,[1] was active in Federalist Party politics during the Thomas Jefferson and James Madison administrations, and later was one of the largest financiers of the early Industrial Revolution in the United States.

Partnering with a number of fellow merchants in Beverly and Salem, including George Cabot, he invested in numerous privateer ventures that brought him a small fortune by the close of the war.

The Embargo of 1807 had a negative impact on Thorndike's trade, and drove him to become a particularly radical opponent of the Democratic-Republican Party under the presidencies of Thomas Jefferson and James Madison.

The term "gerrymander" is attributed to the outcome of a dinner party at Thorndike's Boston home in February 1812, "where Elkanah Tisdale, a miniature painter, drew wings on the salamander shaped map of the new Republican-leaning election district in Essex County.

Thorndike and his son, Israel, Jr., received a twenty percent ownership stake in the company, which became the first successful textile manufacturer in the country and which inaugurated the Industrial Revolution in the United States.

[14] Thorndike used his immense wealth for philanthropic enterprises, such as to buy the map collection of German scholar Christoph Daniel Ebeling.

[16] In 1825, along with his neighbor, Daniel Webster, who owned the adjoining townhouse, he hosted a dinner in the honor of the Marquis de Lafayette on the fiftieth anniversary of the Battle of Bunker Hill.