The total rose by 8,000 in the ten years to 1831, by another 11,000 in the next decade and a further 10,000, to 57,020 in 1851. This was to be a population peak not exceeded for another century and the 30-year increase was the fastest rise of any era for which records are available.
The next 60 years saw a steady decline of about 1,000 per decade, but the combined effects of deaths in the First World War and the influenza epidemic of 1917 saw a further decline to 49,701 in 1921.
After that the population began to rise rapidly, the biggest growths being recorded between 1939 and 1951 and then in the 1960s, 70s and 80s, when the population grew on average by nearly 1,000 a year, to reach 84,000 in 1991, boosted by a new wave of immigrants filling jobs in the islands burgeoning finance industry. This was above the ceiling of 80,000 which had been identified by the States during the 1980s as a figure the island should be aiming not to exceed. Whether because of States policies or external factors, net immigration dropped back and in the 90s the population grew by only 3,000 over ten years. The latest estimates show that a fresh wave of immigrants caused annual growth averaging over 800 from 2005 to 2008 and by 2009 the population had reached 92,500.
The next census in 2011 will provide a more accurate figure, but there are those who believe strongly that the size of households has been underestimated by successive censuses because many lodgers and illegal tenants are not recorded, and that the true population of Jersey probably now exceeds 100,000.
The growth in the second half of the 20th century does not compare with that of the first half of the 19th century. The population doubled between 1821 and 1851, and even if a figure in excess of 100,000 is accepted today, it has still not doubled again.
The population density of roughly 800 people per square kilometer is lower than Guernsey's 990, but way ahead of the average 390 in England. Jersey is estimated to be more crowded than Mauritius and Barbados, but somewhat less densely populated than Malta and Bermuda.