Humans have lived in small numbers on Saltholm since the Middle Ages and probably before.
The population has decreased from a peak of 298 people in 1916, when the island was fortified during World War I, to two people as of January 2020.

The existence of the island is first attested in 1230, when King Valdemar II of Denmark is recorded as having given Saltholm to Bishop Niels Stigsen of the see of Roskilde.
For centuries, the island was used to quarry limestone, which was used in nearby Copenhagen and elsewhere; in 1289, the town lord of Copenhagen is recorded to have granted quarrying rights on Saltholm and quarrying continued until as late as 1935.
The island was also traditionally used as pasture land for the cattle of the people of the nearby Danish island of Amager.
The cows of Saltholm were commemorated in the late 19th century by the Danish painter Theodor Philipsen, who travelled frequently to the island to paint its cattle and treeless landscapes.

Saltholm was used as a quarantine station between 1709 and 1711 when Copenhagen suffered plague and cholera outbreaks.
Travellers wishing to land in the city were required to stay in quarantine on the island for 40 days.
In 1873, a private company, the Saltholmlaug, acquired the island from the state and still owns it today.

The island's position in the middle of the Øresund gave it some military significance during the two World Wars.
In 1912, the Danish government constructed the Flakfortet (sand-shoal fort) on the Salthom Flak sands just north of the island proper, stationing a number of artillery pieces ranging in calibre from 47 mm to 290 mm.
Most of the guns were mounted on barbette carriages and protected by armoured shields and concrete and earthen ramparts.
The fort was still active at the start of World War II; although old, its guns were still seen as a strong deterrent.

Saltholm was the site of an incident resulting in the loss of the British submarine HMS E13, which ran aground on the island on 17 August 1915 due to a faulty compass.
Two days later, two German destroyers attacked the submarine while it was still stranded on the shoreline as the crew worked to refloat the vessel.
Fifteen of the submariners were killed before Danish torpedo boats intervened to deter the attackers.
The violation of the country's neutrality outraged the Danish government, prompting a diplomatic protest to the Germans, and the casualties were given high-profile official funerals by the Danish navy.
The surviving crew were interned in Denmark until the end of the war in November 1918, and the wrecked submarine was scrapped.
The commander of the E13, Lt Cdr Geoffrey Layton, went on to have a distinguished career in the Royal Navy and commanded the British Eastern Fleet during the Second World War.

The island was for many years considered as a possible location for a new international airport and fixed link between Denmark and Sweden.
The nearby Copenhagen Airport at Kastrup has long been the busiest airport in Scandinavia but has suffered from an acute shortage of space and its proximity to built-up areas.
In 1965, the Nordic Council agreed in principle to build a new international airport on Saltholm, to replace the airport at Kastrup, and to construct a bridge-and-tunnel link across the island to connect Copenhagen and Malmö.
The proposal was strongly supported by Scandinavian Airlines System, the main user of Copenhagen Airport.
The plan envisaged building two pairs of runways, which would be carrying up to 20 million passengers a year by 1990.
A 9 km (5.6 mi) bridge would connect it to Malmö and a 5 km (3.1 mi) tunnel would link to Kastrup on the Danish side.
The project was costed at the equivalent of £250 million in 1967 (£3.1 billion / €3.4 billion at 2009 prices).

The plan was approved by the Danish parliament in 1969 with completion scheduled for 1985.
However, it was repeatedly delayed; contributory factors included the 1973 oil crisis and its economic fallout, a slump in air travel, and opposition from campaigners concerned about the impact on the fragile environment i
Humans have lived in small numbers on Saltholm since the Middle Ages and probably before. The population has decreased from a peak of 298 people in 1916, when the island was fortified during World War I, to two people as of January 2020.
The existence of the island is first attested in 1230, when King Valdemar II of Denmark is recorded as having given Saltholm to Bishop Niels Stigsen of the see of Roskilde. For centuries, the island was used to quarry limestone, which was used in nearby Copenhagen and elsewhere; in 1289, the town lord of Copenhagen is recorded to have granted quarrying rights on Saltholm and quarrying continued until as late as 1935. The island was also traditionally used as pasture land for the cattle of the people of the nearby Danish island of Amager. The cows of Saltholm were commemorated in the late 19th century by the Danish painter Theodor Philipsen, who travelled frequently to the island to paint its cattle and treeless landscapes.
Saltholm was used as a quarantine station between 1709 and 1711 when Copenhagen suffered plague and cholera outbreaks. Travellers wishing to land in the city were required to stay in quarantine on the island for 40 days. In 1873, a private company, the Saltholmlaug, acquired the island from the state and still owns it today.
The island's position in the middle of the Øresund gave it some military significance during the two World Wars. In 1912, the Danish government constructed the Flakfortet (sand-shoal fort) on the Salthom Flak sands just north of the island proper, stationing a number of artillery pieces ranging in calibre from 47 mm to 290 mm. Most of the guns were mounted on barbette carriages and protected by armoured shields and concrete and earthen ramparts. The fort was still active at the start of World War II; although old, its guns were still seen as a strong deterrent.
Saltholm was the site of an incident resulting in the loss of the British submarine HMS E13, which ran aground on the island on 17 August 1915 due to a faulty compass. Two days later, two German destroyers attacked the submarine while it was still stranded on the shoreline as the crew worked to refloat the vessel. Fifteen of the submariners were killed before Danish torpedo boats intervened to deter the attackers. The violation of the country's neutrality outraged the Danish government, prompting a diplomatic protest to the Germans, and the casualties were given high-profile official funerals by the Danish navy. The surviving crew were interned in Denmark until the end of the war in November 1918, and the wrecked submarine was scrapped. The commander of the E13, Lt Cdr Geoffrey Layton, went on to have a distinguished career in the Royal Navy and commanded the British Eastern Fleet during the Second World War.
The island was for many years considered as a possible location for a new international airport and fixed link between Denmark and Sweden. The nearby Copenhagen Airport at Kastrup has long been the busiest airport in Scandinavia but has suffered from an acute shortage of space and its proximity to built-up areas. In 1965, the Nordic Council agreed in principle to build a new international airport on Saltholm, to replace the airport at Kastrup, and to construct a bridge-and-tunnel link across the island to connect Copenhagen and Malmö. The proposal was strongly supported by Scandinavian Airlines System, the main user of Copenhagen Airport. The plan envisaged building two pairs of runways, which would be carrying up to 20 million passengers a year by 1990. A 9 km (5.6 mi) bridge would connect it to Malmö and a 5 km (3.1 mi) tunnel would link to Kastrup on the Danish side. The project was costed at the equivalent of £250 million in 1967 (£3.1 billion / €3.4 billion at 2009 prices).
The plan was approved by the Danish parliament in 1969 with completion scheduled for 1985. However, it was repeatedly delayed; contributory factors included the 1973 oil crisis and its economic fallout, a slump in air travel, and opposition from campaigners concerned about the impact on the fragile environment i
Saltholm