By 1835 the Township was a thriving mill town and impetus was further given to this growth by the arrival of the Morris and Essex Railroad. Some people had wanted a canal instead, but the railroad interests won, and the community was linked to the big cities to the east and the coal regions to the northwest.

Community life began to crystallize. From a rough-logged place of worship which legend places on Main Street in mid-18th Century, grew the Springfield Presbyterian Church, the principal church for the area for many years. The White Oak Ridge Chapel founded in 1831 was the first permanent church. Today there are ten houses of worship representing almost all faiths.

Public schools were built, the White Oak Ridge School before 1830, one on Old Short Hills Road at the head of Parsonage Hill Road before 1857. In 1964 Millburn has seven elementary public schools, high and junior high schools, and three independent elementary schools.

Millburn has had many names – Rum Brook, Riverhead, Vauxhall, Milltown, Millville, but in 1857, the name Millburn was finally decided upon. Scotchborn Samuel Campbell's first "mill- on-the-burn" was remembered when the time for choosing a name came.

In 1857 a new spirit of independence caused this northern part of Springfield to separate from its parent and become the Township of Millburn.

A few years later two separate events in opposite ends of the Township accelerated its growth. One was the first speculative real estate development begun by the Wyoming Land and Improvement Company in 1872, which added the Wyoming Section. The other was the coming of Stewart Hartshorn, who in 1877 began to build on his newly-acquired 1552 acres his dream of an ideal village which he called "Short Hills."