The name Howth is thought to be of Norse origin, perhaps being derived from the Old Norse Hǫfuð ("head" in English). Norse Vikings colonised the eastern shores of Ireland and built the settlement of Dublin as a strategic base between Scandinavia and the Mediterranean.
After Brian Ború, the High King of Ireland, defeated the Norse in 1014, many Norse fled to Howth to regroup and remained a force until their final defeat in Fingal in the middle of the 11th century. Howth still remained under the control of Irish and localized Norse forces until the invasion of Ireland by the Anglo-Normans in 1169.
Without the support of either the Irish or Scandinavian powers, Howth was isolated and fell to the Normans in 1177. One of the victorious Normans, Armoricus (or Almeric) Tristram, was granted much of the land between the village and Sutton. 
Armoricus built his first castle near Howth harbour and was the first of many Lords, Barons and Earls of Howth. He took the name St. Lawrence in honour of the Saint's day of August 10th, and created a dynasty that would last for centuries.
The various generations of St. Lawrence's held a firm view on what the lands of Howth were used for. Some would argue that, generally, this was good thing as it stopped Howth from being abused in terms of inappropriate housing etc. 
Howth was a trading port from at least the 14th century, with both health and duty collection officials supervising from Dublin, although the harbour was not built until the early 19th century.
Before the 19th Century, Howth was sparsely populated. Although only 9 miles (14.5 km) from the centre of Dublin, there was virtually no public transport route from Dublin to Howth making it relatively isolated. Any journey to and from Dublin was long and often dangerous due to frequent highway robberies, which would have meant that there was little incentive to live in Howth and to also work or trade in the city. 
Merchants would mostly come to Howth by sea, and would often barter for their goods. (Being a fishing village, the main 'currency' would have been herring!) This meant that Howth was relatively self sufficient.  
The Mail Packet and Howth Harbour
However, after the Acts of Union in 1801 and the subsequent moving of the Irish parliament to London, communication links from London to Dublin became more important.
The British Government needed to find a suitable harbour for the mail packet (postal service) and chose Howth, as sailing there was safer and quicker than trying to sail into Dublin itself. This was because before steam power, Dublin bay was notorious for the high number of shipwrecks due to its "shifting sand banks, strong tidal draw and treacherous winds"  Also, the average time taken from Dublin to Holyhead was 17 hours 7 minutes. The move to Howth reduced this to about 15 hours.  This would be further reduced to less than 6 hours when steam packet boats were introduced in 1822. 
Because of this move of the postal service to Howth, the first major road links to Dublin were built. This did improve the journey, but one of the arguments used against Howth by the advocates of Dunleary (now Dún Laoghaire) for the mail packet was that coaches were often robbed at Sutton as they tried to exit the peninsula (at that time Sutton was open countryside.) 
Despite these arguments, the work on the harbour was completed in 1817.
The railway link
In order to tap into the profitable traffic that the mail boat brought, the Dublin and Drogheda Railway Company planned to build a branch from their Dublin to Drogheda line out to Howth harbour.  
However, before the branch line was completed, silting was causing major problems for the harbour, requiring frequent dredging to accommodate the mail packet. Eventually it was decided that this was too costly and the service was relocated to Dunleary (which was renamed to Kingstown after a visit from George IV). 
Notwithstanding the loss of mail boat, the branch railway line was completed and the first train arrived in Howth on the 30th May 1847.
Howth as a tourist attraction
One of the main attractions for Howth was bathing which was presumed to have noteworthy healing powers. One of the first tenants in Earlscliffe, Pauline McClintock-Bunbury, was supposedly attracted to the property because of the bathing. 
However, even with these attractions, the lack of the mail boat meant that the railway line started its life with heavy losses. Therefore, to encourage people to use the service, the railway company tried to take advantage of the health and holiday attractions at Howth and offered first class tickets that included the use of changing cubicles on Balscadden beach in Howth!  
The increase in day visitors to Howth did encourage the establishment of a number of hotels. These included the Royal Hotel (later renamed to the Baily Court), the St. Lawrence, Claremont Lodge (later renamed to Howth Lodge), the Marine at Sutton, and the Deerpark. Out of all of these, only the Marine is still open (although there is talk of the Deerpark re-opening). 
Increase in residential properties
The better communications also meant that it was quicker and safer to travel to Dublin, and with this, the number of residential properties started to grow during the 19th Century.
A lot of these houses were built primarily as summer residences for the rich and famous, with the majority being built on the Hill of Howth overlooking Dublin Bay. Earlscliffe was built around this time.
The Tram arrives
One of the challenges of living on the south side of the Hill of Howth was that the roads were not great on this side of the hill. There had been talk of a tramway in Howth as far back as 1883, but in those days there was only horse power or possibly steam power, which was unsuitable for Howth due to the steep gradients.
However, by the end of the 19th century, electric traction arrived and on the 17th June 1901 the tram line from Sutton to the Howth Summit was opened, with the final leg of the tram line from the Summit to Howth railway station opening on the 1st August 1901.
There was even a request stop for Earlscliffe. One of the previous tenants mentioned that the tram drivers would drop them off at the Earlscliffe stop and then wait for them to get safely to Earlscliffe and flash the home lights before heading off up or down the hill!
When the Howth Tram opened in 1901, this was expected to grow the population even further. This growth did happen, but it wasn't because of the tram.
By the early 20th Century, many of the owners of the fine houses being built on the Hill of Howth owned cars. This meant that the tram was mostly used by tourists and only really used in the summer, and that depended upon the weather.
With a result, the tram never made any money and was finally closed in 1959. 
The old track that the tram ran on that goes past Earlscliffe was turned into a roadway (Carrickbrack Road) and as the century progressed, the roads in Howth greatly improved.
As for Howth harbour, despite its initial history, it went from strength to strength.
In the mid 1980s, major work took place to transform it from a small fishery harbour to the largest on the east coast. This included an RNLI lifeboat station, a marina and a new middle pier for the fishing fleet.
It is interesting to read the population statistics for Howth over the last almost two centuries as they demonstrate the high growth in this period. 
Here are some thoughts on the graph and figures:
- Interesting that there was no real decrease in the population during the famine years (1845 to 1850). Maybe this was due to the availability of large quantities of fish?  .
- There was a large building programme in Howth and Sutton in the 70s. In 1980, Professor Vincent McBrierty reported that in the previous eight years, fourteen new streets were created in Howth. 
- Some might think that the decrease in the 80s was partly related to the Pope's visit in 1979 when he preached against contraception and abortion! However, it is more likely that the drop in population was linked to the sharp rise in unemployment at that time! 
In 1999, Fingal County Council recognised the exceptional character of Howth by making the Howth Special Amenity Area Order. The Order protects many of the special qualities of the area and aims to preserve and enhance the character and special features of Howth. The Howth Order was confirmed by the Minister for the Environment on 16th May 2000. Earlscliffe gardens are included in this order. 
As the 21st century progresses, Howth population has steadied at over 8,000 people. Even the recession in 2008 didn't seem to affect the numbers.
The harbour has major plans for improvements, with suggested upgrades to the east pier, and works have started to the middle pier with the "provision of an additional 120m of trawler berths".
Other significant events and Howth trivia
Grace O'Malley and Howth Castle
In 16th century Ireland, Grace O'Malley, also known as Gráinne O'Malley or Gráinne Mhaol, became known as the 'Pirate Queen' because of her exploits as a sea-captain and a political activist.
It is said that during a trip to Dublin, Grace went to visit Howth Castle, home of the Earl of Howth, but was told when she got there that the family was having dinner and the castle gates were closed to her. She got so angry at being shut out that she abducted the Earl's grandson and heir, Christopher St Lawrence, and only released him when the Earl promised to keep the gates open to unexpected visitors and to set an extra place at every meal. This arrangement was kept in place until today! 
Howth Gun running
On the 26 July 1914, 900 rifles were landed at Howth by Erskine Childers for the Irish Volunteers. Many were used against the British in the Easter Rising and in the subsequent Anglo-Irish War. 
Leopold and Molly Bloom
Howth Head is the location where Leopold Bloom proposes to Molly in James Joyce's Ulysses and is mentioned in the lyrics of the title track of Kate Bush's 1989 album, The Sensual World a song inspired by Molly Bloom's soliloquy in "Ulysses". :
'...took six big wheels and rolled our bodies / off of Howth Head and into the flesh, mmh, yes...'. Kate Bush - The sensual World 
For more information
-  https://en.wikipedia.org/wiki/Howth
-  As discussed in "Howth: A Centenary of Sailing" by WM Nixon, published in 1995 by Howth Yacht Club, Dublin. ISBN 095271440X
-  As discussed in "A Guide to Dublin Bay: Mirror to the City" by John Givens, published in 2006 by The Liffey Press. ISBN 1905785089.
-  https://en.wikipedia.org/wiki/Howth_Head ,
-  As discussed in "The Howth peninsula: Its history, lore & legend", by Vincent J McBrierty, Publisher: North Dublin Round Table (1981) ISBN: 0950755303
-  As discussed in "Through Streets Broad and Narrow: A History of Dublin Trams" by Michael Corcoran, published in 2000 by Midland Publishing. ISBN 1857801105
-  https://airo.maynoothuniversity.ie/mapping-resources/airo-research-themes/historical-mapping/population-change-1841-2002-dublin seen on 10th Oct 2021.
-  As discussed in the article "Baby Boomers" by Brendan Walsh, as seen at http://www.irisheconomy.ie/index.php/2009/06/18/baby-boomers/ seen on 10th Oct 2021.
-  As discussed in "Howth And Her Trams: Stories And Sketches Of The Howth Tram" by Jim Kilroy, published in 1986 by Fingal Book Publishers. ISBN 185186010X
-  As discussed in "Holyhead Services 1561-2011" eBook, as seen at http://www.thinkscape.ie/stenaline/holyhead_1561-2011.pdf seen on 10th Oct 2021.
-  As discussed in http://www.turtlebunbury.com/family/bunburyfamily_lisnavagh/CaptainWillMcCB/bunburyfamily_lisnavagh_captainwill18521866.html
-  As discussed in "Major development works planned for Howth harbour " by Mark Hilliard, Irish Times, Jan 18 2018. As seen at https://www.irishtimes.com/news/ireland/irish-news/major-development-works-planned-for-howth-harbour-1.3359208
-  See https://www.fingal.ie/howth-special-amenity-area-order
-  Taken from https://www.aznations.com/population/ie/cities/howth
-  See https://visithowth.ie/grace-omalley/
This page was last updated on 19-Oct-2021.