County Donegal's largest third-level institution, Atlantic Technological University (ATU) Letterkenny, is located in the town, as are St Eunan's College, Highland Radio, and a Hindu temple.

The site of the ancient seat of the Ó Canannain was near Letterkenny (the largest town of County Donegal only since the 1950s), which is said to represent the countryside of the O'Cannons (English translation).

The waters of the Atlantic had not yet retreated from the basin of the Swilly, whose estuary at that time extended up almost as far as New Mills – proof of this may be found in those alluvial flatlands between the Oldtown and the Port Road.

The receding of the waters of the Atlantic eastwards enabled progress, and with the building of bridges etc., the town of Letterkenny started to take the shape it has today.

In the wake of the Plantation of Ulster (which began around 1609), when a 4 square kilometres (990 acres) area was granted to a Scotsman Patrick Crawford, the compact community formed.

During the Irish Rebellion of 1798, on 12 October, a large French force consisting of 3,000 men, including Wolfe Tone, attempted to land in County Donegal near Lough Swilly.

After Wolfe Tone was captured he was held for a short time at Laird's Hotel (opposite the Market Square) in the Main Street of Letterkenny[11] before being transferred to the nearby Derry Gaol.

In 1824, when the first description of Letterkenny as a modern town was written, it was stated that: "Within half a mile is the Port of Ballyraine, whither vessels of 100 tons bring iron, salt and colonial produce and whence they export hides and butter".

Malin Head's climate is classified as Temperate Oceanic (Köppen Cfb) and is significantly milder than some other locations in the world at a similar latitude; this is due to the station's position near the Atlantic Coast and exposure to the warmth of the Gulf Stream.

Snow is relatively uncommon and the station receives on average 20 days of recorded snowfall per year, the vast majority of this occurring between December and March.

It features a sloping grass roof situated above a broad band of aluka matt cladding and a runway-like ramp to the first-floor concourse.

The College, as it is known locally to distinguish it from the cathedral and GAA club,[27] is named after Adomnán or Eunan (the Abbot of Iona who was native to Tír Chonaill, mainly modern County Donegal, and is patron saint of the Roman Catholic Diocese of Raphoe).

The town is the northwest region's major shopping centre[31] and helps to serve outlying areas including rural County Donegal and Derry.

[citation needed] In August 2012, two winning Lotto tickets using the same numbers for the same draw were bought at two different locations in the town – Mac's Mace on the High Road and The Paper Post on Main Street.

[41] In April 1970, the Donegal News reported that local politicians acknowledged "a very real problem" in attracting industrialists to come to the town, even in spite of grants being available to do so.

As the main commercial centre of north Donegal, Letterkenny also has a host of financial service institutions, legal firms and small businesses.

[53] In 2008, Letterkenny represented Ireland in the Entente Florale, having scooped Gold in the Large Urban Centre category of the 2007 National Tidy Town Awards.

Along with the daily street performances on Market Square, An Grianán Theatre and The Courtyard Shopping Centre, song, fiddle, harp and dance contests are also featured.

Brendan Behan, while holidaying in County Donegal on Tuesday 22 August 1961, walked there to watch Eamonn Andrews interviewing him in the newsreel Meet the Quare Fella.

[64] Letterkenny is a favoured nightlife location for the local catchment area, and also for the rest of Ulster — particularly at weekends and especially for visitors from the nearby city of Derry.

[citation needed] The closest professional football club is League of Ireland Premier Division side Finn Harps in Ballybofey, 12 miles from Letterkenny.

It has forged links with several New Zealand rugby fraternities[citation needed] due to the fact that Dave Gallaher, the first captain of the All Blacks, was born in Ramelton, a village eight miles (13 km) from Letterkenny.

The club's rugby ground in Letterkenny was named the Dave Gallaher Memorial Park in his honour in November 2005 by a visiting contingent of All Black players, led by captain Tana Umaga.

There is a campaign being run by a local councillor for the construction of a horse racing track and facilities on land at the Big Isle, on the outskirts of the town.

Only a couple of decades later, the independence of the Irish Free State from the rest of the UK resulted in rail companies operating across two jurisdictions where there had previously been one.

This had devastating effects on an already fragile economic situation, resulting eventually in the final closure of all parts of the rail system in the area by December 1959.

The strategically important Belfast-Derry railway line is to be upgraded to facilitate more frequent trains and improvements to the permanent way such as track and signalling to enable faster services.

[90] In December 2019, the Environmental Protection Agency (EPA) cited Letterkenny as having higher levels of air pollution than the Indian capital New Delhi.

Lonely Planet lists Donegal, in which Letterkenny is located, as one of its Irish counties in which visitors should not drink the tap water due to its featuring "toxic chemicals".

[95] The Commission stated that large amounts of THM cause diseases of the liver, kidneys and central nervous system, cancers of the bladder and colon, and damages to foetuses during pregnancy.