Long Island has approximately 8 million residents when the full geographic island is counted, including Brooklyn, Queens, Nassau County, and Suffolk County. Together, those four counties recorded 8,063,232 residents in the 2020 U.S. Census. If you mean only Nassau and Suffolk counties, as many locals do, the combined count was 2,921,694 residents, or about 3 million.
Why Are There Two Different Population Figures?
The answer depends on how “Long Island” is being used. Geographically, Brooklyn and Queens occupy the island’s western end, even though both are boroughs of New York City. Their residents are included when calculating the population of the full island.
In everyday conversation, business descriptions, and real estate listings, “Long Island” often refers specifically to Nassau County and Suffolk County. This regional usage explains why one source might describe Long Island as having about 3 million people while another gives a figure of about 8 million. Both can be reasonable rounded answers, provided the geographic definition and population year are clear.
Population by County
The following figures are April 1, 2020 Census counts, giving each county the same reference date. Brooklyn is also known as Kings County. Annual population estimates published after the census may differ from these figures.
2020 Census Counts
| County or Area | 2020 Census Population |
|---|---|
| Brooklyn (Kings County) | 2,736,074 |
| Queens | 2,405,464 |
| Nassau County | 1,395,774 |
| Suffolk County | 1,525,920 |
| Nassau and Suffolk Combined | 2,921,694 |
| Full Geographic Long Island | 8,063,232 |
Source: U.S. Census Bureau, 2020 Census counts for Kings County, Queens County, Nassau County, and Suffolk County. Combined totals were calculated by adding the corresponding county counts.
Where Do Most Long Islanders Live?
Brooklyn and Queens accounted for approximately 64 percent of the four-county population in the 2020 Census. These densely developed boroughs contain the largest share of the island’s residents, while Nassau County and western and central Suffolk County include extensive suburban neighborhoods, villages, hamlets, and commercial centers.
Farther east, development generally becomes less dense, with farmland, vineyards, preserves, and coastal communities across the North Fork and South Fork, including the Hamptons. Seasonal visitors and second-home occupants can make some communities much busier during summer, but that seasonal presence is different from the resident population measured by the census.
Key Facts & Details
| Category | Information |
|---|---|
| Full Geographic Population | 8,063,232 residents across Long Island’s four counties in the 2020 Census, or approximately 8 million. |
| Nassau and Suffolk Population | 2,921,694 residents in Nassau County and Suffolk County combined in the 2020 Census, or about 3 million. |
| Population Reference Date | April 1, 2020; subsequent annual estimates may differ. |
| Counties Included | Kings County (Brooklyn), Queens County, Nassau County, and Suffolk County. |
| State | New York State. |
| Most Populous County on the Island | Kings County (Brooklyn), with 2,736,074 residents in the 2020 Census. |
| Common Local Meaning | “Long Island” often refers only to Nassau and Suffolk counties. |
| Primary Data Source | U.S. Census Bureau QuickFacts. |
For a quick answer, think approximately 8 million people for the full geographic Long Island and about 3 million for Nassau and Suffolk counties alone. When comparing population figures, check both the area included and the year of the count or estimate so that the numbers describe the same place and period.