When Samuel was three years old, his parents emigrated to the British colonies in America and settled in present-day Chowan County, North Carolina down. He received his school education, however, in New England. He then studied law in North Carolina and opened a law office in Edenton. Between 1760 and 1775 he was a deputy in the Parliament of colonial North Carolina. At the same time he was employed in the administration of the Supreme Court of the colony. At the outbreak of the American Revolution, he was on the side of the Americans. He took part in some meetings in North Carolina in part to prepare for independence.
In 1779, Johnston was elected to the Senate from North Carolina. The Senate appointed him delegate for the U.S. Continental Congress the years 1780-1781 ., There he was after the adoption of the " Articles of Confederation ", the first constitution of the United States, which lasted until 1788, was elected first president. Johnston rejected the choice from, however. Instead, he returned to North Carolina and served from 1783 to 1784 again in the Senate of the country. In 1787 he was elected to succeed Richard Caswell Governor of North Carolina.
Governor of North Carolina
Overall, Johnston was elected three times in succession to the Governor. His term began on December 20, 1787 and ended on 17 December 1789. Right at the beginning of his third term, he resigned from his office to switch as a Senator in Congress. As governor, he led the Assembly in 1788, which ratified the new U.S. Constitution. Otherwise his term passed without highlights. There was still the border conflict in the west with the self-proclaimed "State of Franklin " under the leadership of John Sevier and the construction phase of the country after the war was in full swing.
Johnston, who belonged to the Federalist Party, remained until 1793 Senator in the U.S. Congress. Between 1800 and 1803 he was a judge at a district court in North Carolina. This was his last public office. He died in 1816 at his plantation called " Hayes Plantation " near Edenton in Chowan County.
His nephew, James Iredell, was also later governor.