Thomas McKean was a lawyer, a judge, and a patriot, with strong ties to both Delaware and Pennsylvania. Present at both Continental Congresses, an avid promoter of republicanism, and a witness to the key points in the American Revolution, McKean is often forgotten as a founder of the new United States of America. Thomas McKean had a hand in influencing the judicial, political, and structural aspects of the new country.

Thomas McKean was born on March 19, 1734, in New-London, Chester County, Pennsylvania to William and Letitia McKean, two Irish immigrants. He was the second oldest of three boys and a girl. His father, William, was a poor tavern-keeper, and Letitia passed away before Thomas McKean had seen his eighth birthday.

Before her death, Letitia McKean had stressed to her children the importance of education. At the age of nine, Thomas McKean went to Reverend Francis Alison's academy in New London with his older brother, Robert. Here, the boys were taught Latin, Greek, mathematics, rhetoric, and philosophy. The philosophies and teachings of Reverend Alison stayed with Thomas McKean throughout his career. It was with Alison that McKean first studied the ideas of liberty that would become a central part of his life during the years of the Revolution. Historian John M. Coleman said in his book Thomas McKean: Forgotten Leader of the Revolution, "It would be too much to expect that American independence was visible...but the spirit of freedom was there, and a deep concern for politics."

After studying with Alison, the McKean brothers parted ways in 1750 when Thomas traveled to New Castle to study law with cousin, David Finney. Finney, a prominent lawyer, helped him to complete his law degree before McKean turned 21 years-old. With the aid of his cousin's influence, McKean saw the judicial side of the early Republic first-hand. Finney was able to help McKean to be assigned as a clerk to the prothonotary of the New Castle court of common pleas. Shortly after, McKean was named deputy prothonotary and register for the probate of wills for Newcastle County. According to Coleman, New Castle was a "court town and center for political activity," and the right place for an aspiring lawyer like McKean to be working.

By serving in the various positions, McKean gained invaluable knowledge of law and the inner workings of the judicial system. In addition, he made key relationships with certain lawyers of the time. These experiences would assist him as he progressed in his law career. On October 7, 1754, Thomas McKean was officially admitted to the Delaware bar. For the next few years, McKean made a name for himself as a successful lawyer.

In 1762, McKean, as he himself said in his autobiography entitled Biographical Sketches, "for the first time ventured out on the stormy sea of politics." He was elected to be a member of the Assembly of the Lower Counties for New Castle County. Two parties existed in Delaware at the time, the Court and the Country, the latter of which McKean supported. McKean described the Country party in his sketches as "those who wished an independence of judges and an impartiality in the laws."

While his career progressed, McKean's personal life was changing too. In July 1763, McKean married Mary Borden. The couple had six children. In 1773 however, Mary died. After a short courtship, Thomas McKean married Sarah Armitage who gave birth to the couple's five children.

The passing of the Stamp Act in 1765 caused major dissent among the American colonists including Thomas McKean. He and another Delaware representative, Caesar Rodney, traveled to the Stamp Act Congress which first met on October 7, 1765, in New York. At this convention, McKean was often frustrated with how moderately many of the delegates acted in regard to making changes. G. S. Rowe's Thomas McKean: The Shaping of an American Republicanism makes the important point that the Congress did give McKean the opportunity to "discuss the legal and constitutional issues dividing the American people with some of the knowledgeable men in colonial America." After leaving the Congress, McKean was more aware than ever before of the discontent in the other colonies and the inevitable need for action.

As tensions grew in the colonies, McKean attended the First Continental Congress on September 6, 1774. Here, he spent much time with John Adams, whose proactive nature was similar to that of McKean's own. He helped to draft the Declaration of Rights and Resolves. He and other members of the Congress agreed during this Congress to abstain from trade with England. In the spring of 1775, McKean returned for the Second Continental Congress.

After the colonies decided to officially separate from Great Britain, Thomas McKean served in the Fourth Battalion of the Pennsylvania Associators. Throughout the war McKean kept in touch with his wife. Once, he wrote home saying, as Rowe restated in his work, "these were the first times I ever ordered to be fired against human beings — if I may be allowed to call the Enemies of Mankind such." Evidently, the object of the war, freedom, and liberty, was still a strong motivation to McKean the other patriots during the long years of battle.

During the Revolutionary War, Thomas McKean also assisted in the writing of the Articles of Confederation. In 1781, he voted to ratify them. When Samuel Huntington stepped down from President of Congress in the summer of 1781, McKean was elected to replace him. Herbert E. Klingelhofer described McKean's term as "singularly placid and uneventful" because there were not any groundbreaking issues for McKean to confront. As president, he corresponded with General George Washington and was in office when the war was won in the Battle of Yorktown.

During the mid 18th century, the Supreme Courts of the states were the most prestigious judicial institutions, as mentioned in John M. Coleman's work. McKean was sworn in as Chief Justice of the Supreme Court of Pennsylvania in 1777 and would serve on the court for the next 22 years. As prestigious as the courts were, they were also young and still working to establish the power necessary to influence to governmental workings of the new country. McKean's court was also responsible for setting many precedents for the future of the American judicial system. Coleman argues that it was not John Marshall who was the father of the American judicial system but rather McKean who laid the groundwork for justices like Marshall.

Although a member of the Continental Congress representing Delaware, Thomas McKean's signature does not appear on the copy of the Declaration of Independence, the Goddard Broadside. This absence has created great controversy about the exact timing of the signing of the Declaration and where McKean was during it. Today, historians still argue about the legitimacy of the timing of McKean's signature.

Whether Thomas McKean signed the Declaration at the appropriate time or not, Revolutionary War raged on, and he felt the effects. McKean had just been sworn onto the court when he was forced to return to Delaware to serve as the state's Acting President. The president had been captured, and those next in succession were unable to serve. When he arrived, he found the state in disarray. He tried to gather the militia, but many members had already left the state in search of safety or to help the British. With almost all of the state's money taken by the British forces, McKean was forced to borrow funds from Congress.

Although willing to serve "the virtuous part of the people," as he said, McKean was anxious to elect another president so that he could return to his role as Chief Justice of Pennsylvania. In October of 1777, George Read was reelected as Speaker of the Council in Delaware and therefore was entitled to take over the position of Acting President of the state. McKean returned to Pennsylvania where he would be forced to move his family to keep them safe. In a letter to John Adams, McKean said, "I too have had my fair share of anxieties cares & troubles attending the present war."

As the Chief Justice of Pennsylvania, Thomas McKean faced many challenges typical of a new judicial system. McKean was able to greatly influence politics in the state through use of "advisory opinion" in which he would make suggestions to others regarding law but not officially influence any legislature. In a letter to George Read, McKean stated that he promised to "give a little assistance in draughting some bills" to Pennsylvanians in Lancaster. In addition to giving advice, McKean pushed for formalities in the courts, which in some parts of the state were held in taverns. He also demanded attendance to hearings, refusing to reschedule sessions and replying to such requests without what Coleman refers to as "mincing words."

One of the key cases that Thomas McKean oversaw involved the issue of treason in the Revolutionary Period. A man from Bucks County, Pennsylvania had sided with the British in December of 1776 but was captured during the war. McKean disagreed that he had committed treason based on the timing of his establishing allegiance. Instead, McKean, argued, that between May of 1776 and February of 1777, laws in Pennsylvania were ineffective because there was not yet any established American government. Therefore, during that period, the colonists were free to choose a side without committing any act of treason against the government. Through his actions in this case, McKean, according to Coleman, "laid the foundation for the concept of American treason."

In 1799, after recently switching his alliances from the Federalists to the Jeffersonian Republicans, Thomas McKean was elected governor of Pennsylvania. As governor, McKean had a major role in creating a procedure for choosing presidential electors in the election of 1800. The most memorable action taken by McKean during his time as governor was his dismissing of many government officials and replacing them with his own friends. In a letter, McKean wrote about these actions: "I have been obliged, though no Hercules to cleanse the Augean Stables...." Using political influence to put friends into government office has been termed the "spoils system" and was started by McKean.

These actions and Thomas McKean's overall reputation for haughtiness in dealing with other political figures of the time made him many enemies. Newspapers spoke out against the governor and his "spoils system," and the House of Representatives eventually attempted to impeach him. However, with the help of political allies, McKean was able to delay the trial. Thomas McKean finished his third term as governor before the impeachment was made final. McKean served as the governor until 1812.

In 1817, Thomas McKean died and was buried in Laurel Hill Cemetery in Philadelphia. During his time as governor, McKean helped to secure an area in what is now Northern Pennsylvania as a part of the state rather than part of Connecticut. This county was named McKean County in his honor in 1804.