| Year | Population | Year | Population | Year | Population | ||
| 1757 | 670 | 1901 | 948 | 1979 | 3,796 | ||
| 1813 | 1,486 | 1911 | 866 | 1981 | 3,388 | ||
| 1821 | 1,364 | 1926 | 846 | 1986 | 4,268 | ||
| 1831 | 2,053 | 1936 | 832 | 1991 | 6,027 | ||
| 1841 | 2,029 | 1946 | 765 | 1996 | 8,528 | ||
| 1851 | 1,619 | 1951 | 776 | 2002 | 10,151 | ||
| 1861 | 1,497 | 1956 | 1,722 | 2006 | 10,715 | ||
| 1871 | 1,414 | 1961 | 1,753 | 2011 | 12,510 | ||
| 1881 | 1,278 | 1966 | 1,254 | 2016 | 14,585 | ||
| 1891 | 958 | 1971 | 1,296 | 2022 | 17,259 |
Note 1: Census years between 1851 and 1951 exclude St. Patrick’s College
Note 2: Estimated that for years 1851 to 1951 population for St. Patrick’s College was circa 500 to 600 (per archives)
Note 3: Census from 1956 include St. Patrick’s College and a wider area
Archives of St Patricks College, Maynooth – Irish Archives Resource (iar.ie)