1913

Joseph Cook, Member for Parramatta (which then included Baulkham Hills Shire) became the Prime Minister of Australia. Water pipes in Showground Road were connected to the Sydney Water Supply. By 1917 there were water pipes in Baulkham Hills.

1920

Slab huts in Windsor Road , Baulkham Hills, just south east of the crossroads, were used in the filming of "On our Selection".

1920s

Poultry and egg production replaced citrus and stone fruits as the main industry.

1923

A train service from Westmead to Castle Hill replaced the tram. It was extended to Rogans Hill in 1924.

1926

Electricity came to Baulkham Hills and Castle Hill.

1932

The Railway closed mainly due to the advent of the combustion engine used in trucks, cars and buses that, in turn, needed a wider main road.

1933

Population of the Shire was 8, 075.

1956

Population of the Shire was 16, 500.

1960s

Urban development accelerated from this time.

1970

Population of the Shire was 52, 000.

1971

Sewerage connection was available to residents in Baulkham Hills; Castle Hill followed in 1977.

1975

Population of the Shire was 70, 000.

1979

The first stage of Castle Towers Shopping Centre was commenced with additions following in 1982, 1989, 1993, 1999 and 2001.

1980

Population of the Shire was 90, 000. The NSW Department of Environment and Planning began looking at the potential development of the Rouse Hill area.

1988

The Hills Centre for the Performing Arts was opened at Castle Hill.

1991

Population of the Shire was 114, 032.

1997

Baulkham Hills Shire Council obtained title to two significant heritage sites: Castle Hill Heritage Park and Bella Vista Farm.

2000

Population of the Shire was 131, 000

2001

Rouse Hill Regional Centre plans were revealed. Population reaches 147,000.

2004

Bicentenary of the Castle Hill Rebellion and Battle of Vinegar Hill. The former Castle Hill Government Farm was opened as Castle Hill Heritage Park by NSW Governor, Professor Marie Bashir.