Complex sentence: Middlesex Borough was a portion of Piscataway Township, until May 1913 when it was incorporated as a separate entity through the action of the state legislature and local referendum.
Split into simpler sentences: Middlesex Borough was a portion of Piscataway Township, until 1913 when it was incorporated as a separate entity. In May 1913, Middlesex Borough became a borough through the action of the state legislature and local referendum.