 In 1865 and 1867 the railways between Alkmaar and Den Helder and between Alkmaar and Haarlem were built respectively.In the second half of the 20th century, Alkmaar expanded quickly with development of new neighbourhoods.On 1 October 1972, the town of Oudorp and the southern portions of Koedijk and Sint Pancras were added to the municipality of Alkmaar.