The Humber is now an estuary. When the world sea level was lower during the Ice Ages, the Humber had a long freshwater course across what was then the dry bed of the North Sea.
In the Anglo-Saxon period, the Humber was a major boundary, separating Northumbria from the southern kingdom, though at its height Northumbria did cover areas south of the Humber. The Kingdom of Lindsey, which today is Northern Lincolnshire, was part of Northumbria before being lost to Mercia. The name Northumbria came from Anglo-Saxon Norðhymbre (plural) = "the people north of the Humber". The Humber currently forms the boundary between the East Riding of Yorkshire, to the north and North and North East Lincolnshire, to the south.
From 1974 to 1996, the areas now known as the East Riding of Yorkshire, North Lincolnshire and North East Lincolnshire constituted the county of Humberside.
On 23 August 1921, the British airship R38 crashed into the estuary near Hull, killing 44 of the 49 crew on board.
The estuary's only modern crossing is the Humber Bridge, which was the longest single-span suspension bridge in the world from its construction in 1981 until 1998. It is now the eighth longest.
Before the bridge was built, a series of paddle steamers operated from the Corporation Pier railway station at the Victoria Pier in Hull to the railway pier in New Holland. Steam ferries started in 1841, and in 1848 were purchased by the Manchester, Sheffield and Lincolnshire Railway. They, and their successors, ran the ferry until the bridge opened in 1981. Railway passenger and car traffic continued to use the pier until the end of ferry operations.
The line of the bridge is similar to an ancient ferry route from Hessle to Barton upon Humber, which is noted in the Domesday Book and in a charter of 1281. The ferry was recorded as still operating in 1856, into the railway era. The Humber was then one mile (1.6 km) across.
The Humber Forts were built in the mouth of the river for the First World War. Planned in 1914, their construction started in 1915 and they were not completed until 1919. A coastal battery at Easington, Fort Goodwin or Kilnsea Battery, faced the Bull Sands Fort. They were also garrisoned during the Second World War, and were finally abandoned for military use in 1956.
Fort Paull is further upstream, a Napoleonic-era emplacement replaced in the early 20th century by Stallinborough Battery opposite Sunk Island.
Graham Boanas, a Hull man, is believed to be the first man to succeed in wading across the Humber since ancient Roman times. The feat, in August 2005, was attempted to raise cash and awareness for the medical research charity, DebRA. He started his trek on the north bank at Brough; four hours later, he emerged on the south bank at Whitton. He is 6 feet 9 inches (2.06 m) tall and took advantage of a very low tide. He replicated this achievement on the television programme Top Gear (Series 10 Episode 6) when he raced James May who drove an Alfa Romeo 159 around the inland part of the estuary without using the Humber Bridge.
Crossing by swimming
On Saturday 26 August 1911, Alice Maud Boyall became the first woman to swim the Humber. Boyall, then aged 19 and living in Hull, was the Yorkshire swimming champion. She crossed the Humber from Hull to New Holland Pier swimming the distance in 50 minutes, 6 minutes slower than the men's record.
Since 2011 Warners Health have organised the 'Warners Health Humber Charity Business Swim'. Twelve swimmers from companies across the Yorkshire region train and swim in an ellipse from the south bank to the north bank of the river under the Humber Bridge over a total distance of approximately 1 1⁄2 miles (2.4 km).