MacElree was born on December 17, 1859, in West Chester, Pennsylvania. His parents were Mariah (née Buffington) and James MacElree. His Irish-born father had immigrated to Pennsylvania in 1827 and settled in West Chester in 1852; his mother belonged to an old local family. MacElree attended public schools in West Chester, read law with John J. Pinkerton, and gained admittance to the county bar in 1880.[1][2]
MacElree founded the law firm of MacElree Harvey, Ltd., which is still extant,[3] and practiced law in West Chester until his retirement in 1956.[4] He served as Chester County district attorney from 1897 to 1900 and again from 1906 to 1909.[5] He defended six of the men who allegedly lynched Zachariah Walker in 1911. In his reminiscences, MacElree called the victim a "worthless negro from Virginia." As "the legal sage of Chester County," MacElree's defense role was instrumental in obtaining the acquittals from the jury.[6]
A member of the Republican Party,[1] MacElree ran for judge of the Pennsylvania Courts of Common Pleas but lost the election in a landslide to two-term incumbent Joseph Hemphill in 1909. Hemphill had received the endorsement of the Democratic Party and the backing of many Republicans in the election.[7]
An enthusiastic amateur historian, MacElree lectured widely and published privately at least four books and many "sentimental" sketches and essays about the events, people, landmarks, and natural environment of Chester County.[8] Active in the Westminster Presbyterian Church and serving ten years as a deacon in the First Presbyterian Church of West Chester,[9] he helped to establish Sunday schools across the county.[1]
On January 18, 1884, MacElree married Ella Eyre of West Chester. They had three children, two of whom survived to adulthood.[1] Their son, James Paul MacElree, attended the University of Pennsylvania, joined his father's law firm in 1908, and served as presiding judge of the Chester County Orphan's Court.[4][2]
The elder MacElree died of heart disease in East Bradford Township, Pennsylvania, on January 16, 1960, at the age of 100.[4] He was interred at Oaklands Cemetery just outside West Chester.[10]