[2] Following his tenure in the Senate, he served in the Pennsylvania House of Representatives on two occasions, as a county judge, and as a presidential elector.

After a period of practicing law, he became a surveyor in the employ of the Penn family, and then a prothonotary and clerk of the courts of Northumberland County in the 1770s.

In July 1789 he issued a resolution requiring the President to request the Senate's permission to dismiss Cabinet members, but it was defeated by Vice President Adams's tiebreaking vote when Adams convinced Tristram Dalton and Richard Bassett to withdraw their support.

During Senate debates over the Residence Act establishing the site of the U.S. permanent national capital and seat of government Vice President Adams worked with Morris, who preferred Philadelphia as the capital, to defeat Maclay's motion placing it near his landholdings on the Susquehanna River.

[7] In 1908, the home was purchased by William E. Bailey, a descendant of an early Harrisburg iron and steel industrialist family, who made renovations created by city architect Miller Kast to a Georgian Revival style.

[8] The area east of Maclay's Mansion came to be known as "Maclaysburg" (present day Downtown) and extended out to what would become the Pennsylvania State Capitol Complex.

[10] Previously trying to encourage the relocation of the capital to Harrisburg while in the U.S. Senate, Maclay sold ten acres of land to the Commonwealth prior to his death.