Complex sentence: The pressure from residents of other areas of the state to form boroughs led to the Mandatory Borough Act of 1963, which called for all election districts in the state over a certain minimum population to incorporate as boroughs by January 1,1964.
Split into simpler sentences: The pressure from residents of other areas of the state to form boroughs led to the Mandatory Borough Act of 1963. This legislation called for all election districts in the state over a certain threshold in population to incorporate as boroughs by January 1,1964.