40, 000 BC Darug Aborigines (also spelt Dharug, Daruk, Dharuk) inhabited the Shire until the early 1800s, especially around waterholes

1791 Governor Phillip journeyed to the Shire in April

1794 Hawkesbury Road (Old Windsor Road) was developed from Toongabbie Government Farm to the Hawkesbury River. William Joyce received the first land grant in the Shire and by 1811 was operating the Shire's first inn that was located on this road.

1799 Joseph Foveaux was granted 300 acres, which he sold to John Macarthur in 1801. John and Elizabeth Macarthur farmed sheep on this property before establishing them at Camden. Part of this land was later acquired by the Pearce family and became known as "Bella Vista Farm."

1801 Toongabbie Road (Junction Road) was made from Toongabbie Government Farm to Baulkham Hills and then Castle Hill Road (Old Northern Road) was built to the new Castle Hill Government Farm.

1804 The convicts rebelled on 4 March and made a stand for freedom at the Battle of Vinegar Hill on 5 March.

1807 George Suttor of "Chelsea Farm" Baulkham Hills, was the first person in the colony to produce oranges commercially.

1810 Windsor Road was constructed

1811 Castle Hill Government Farm was converted to the first lunatic asylum in the colony. It operated until 1826 when it was relocated to Liverpool.

1823 Most of the land in the southern part of the Shire had been granted by then. As the century progressed these original grants were subdivided into farms.

1826 construction of Old Northern Road, part of the Great North Road, from Castle Hill to Wisemans Ferry began.

1830 more land started to be granted in the northern part of the Shire.

1840 The first school in the Shire, St Simon's School began at the Old Castle Hill Government Farm site.

1856 John Malloy Kelly opened the first general store and post office in the Shire near the corner of Junction and Windsor Roads Baulkham Hills (now the M2).

1886 Castle Hill District Show began at Rogans Hill and moved to Showground Road Castle Hill in 1891.

1890s "Bella Vista Farm" was thought to be the largest orchard in NSW.

1894 A telephone service was extended to the Hills from Parramatta.

1902 Tram from Parramatta to Baulkham Hills commenced with an extension to Castle Hill opened in 1910. This accelerated the subdivision of old estates adjacent to the railway into residential blocks.

1906 Baulkham Hills Shire Council was created on 6 March via the Local Government Act of 1906. The first meeting was held on 16 June at James Pearce's Baulkham Hills residence.

1907 Telephone links were created between the Hills and the Hawkesbury area.

1911 Population of the Shire was 3,498

1913 Sir Joseph Cook, Member for Parramatta (which included the Baulkham Hills Shire) became Australian Prime Minister.

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 Raymond Longford's "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 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.

1960 Population of the Shire was 21,000.

1960s Urban development accelerated from this time.

1965 Population of the Shire was 29,400.

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.

1978 Land in Victoria and Carrington Avenues, Castle Hill, was set aside for an industrial area now known as the Castle Hill Trading Zone.

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. NSW Department of Environment and Planning began looking at the potential development of the Rouse Hill area.

1988 Population of the Shire was 102,000.

1988 The Hills Centre for the Performing Arts was opened at Castle Hill.

1991 Population of the Shire was 114,032.

1996 Population of the Shire was 118,797.

1997 Baulkham Hills Shire Council obtained title to the significant heritage sites: "Castle Hill Heritage Park" and "Bella Vista Farm".

2001 Population of the Shire was 139,404

2001 Rouse Hill Regional Centre plans revealed.

2004 Baulkham Hills Shire Council opened its new "state of the art" Castle Hill Library and Community Centre at Castle Grand.