He served as its president for 36 years, as it became one of the biggest public utilities companies in the United States.

He started practice with his father's law firm, McCarter & Keen, founded in 1845 in Newark, New Jersey.

He ended his partnership with Adams in 1902 to serve as general counsel for the Fidelity Trust Company of Newark.

[4] McCarter became the first president of the Public Service Corporation; he served in that position for 36 years, resigning in 1945 on his 78th birthday.

Under his guidance, the corporation expanded its control from trolley lines to the management of the state's gas, electric and transportation facilities.