Changes in the number of inhabitants is known throughout the population censuses conducted since 1793 in Calais. Note the massive growth in population from 13,529 in 1881 to 58,969 in 1886, a growth of 335.9%; this is because the city of Saint Pierre merged with Calais in 1885. According to the census INSEE of 2008, Calais has 74,817 people (a decrease of 3% from 1999). The town's population ranked 60th nationally, down from 53rd in 1999.
The city's proximity to England has made it a major port for centuries. It is the principal ferry crossing point between England and France, with the vast majority of Channel crossings being made between Dover and Calais. Companies operating from Calais include SeaFrance (currently in liquidation), DFDS Seaways, and P&O Ferries. The French end of the Channel Tunnel is situated in the vicinity of Calais, in Coquelles some 4 miles (6.4 km) to the west of the town. Calais possesses direct rail links to Paris, 148 miles (238 km) to the south. More than 10 million people visit Calais annually.
From medieval times, English companies thrived in Calais. Calais was a particularly important centre in the production and trade of wool and cloth, which outweighed the costs of maintaining the town as part of England. In 1830 some 113 manufacturers were based in Calais and the St Pierre suburbs, the majority of which were English. There are still two major lace factories in Calais with around 700 looms and 3000 employees. The town exports in the early 20th century were lace, chemicals, paper, wines, especially champagne, spirits, hay, straw, wool, potatoes, woven goods, fruit, glass-ware, lace and metal-ware. Principal imports in the early 20th century included cotton and silk goods, coal, iron and steel, petroleum, timber, raw wool, cotton yarn and cork. During the five years 19011905 the average annual value of exports was 8,388,000 (6,363,000 in the years 18961900), of imports 4,145,000 (3,759,000 in 18961900).
As a fishing port, Calais has several notable fishing markets including Les Dlices de la Mer and Hutrire Calaisenne on the Boulevard La Fayette, the latter of which is noted for its oysters, lobster and crabs from Brittany. The Emile Fournier et Fils market on the Rue Mouron sells mainly smoked fish including salmon, trout, herring and halibut.
Place d'Armes is one of the largest squares in the city of Calais, adjoins the watchtower, and during medieval times was once the heart of the city. While Calais was a territory of England (13471558), it became known as Market Square (place du March). Only at the end of English rule did it take the name of Place d'Armes. After the reconquest of Calais in 1558 by Francis, Duke of Guise, Francis II gave Calais the right to hold a fair twice a year on the square, which still exists today, as well as a bustling Wednesday and Saturday market.