How Big Is Long Island (And Why)?

How Big Is Long Island (And Why)?

Exact Answer: 1401 Square Miles (Area)

Long Island is considered to be one of the most populated landmasses in the New York state of the US. It is located in the southeast of the NY state and houses about half of the whole population of the NY state. 

Long Island is separated from the US mainland. There is a proper misconception that Long Island is not an island. Unlike this popular misconception, Long Island is considered an island by the USBGN. 

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How Big Is Long Island?

As the name suggests, Long Island is the longest in the contiguous US landmass (i.e., barring the US overseas territories). Long Island is the third most populated island in the American continent, housing over 8 million residents.

Long Island is 1401 square miles in area, which makes it the largest island of the US landmass barring its overseas territories. The eastern and north-eastern boundary is the mouth of the Hudson River.  

Long island is the most densely populated metropolitan area of the US. Long Island is 118 miles (190 kilometers) in length and 23 miles (37 kilometers) in width. It is worth noting that Long Island has a long coastline of around 1600 miles. 

For a clearer picture of the population of Long Island, consider the fact that it is the most densely populated region of the US (5595 residents per square mile). 

Long Island is divided into four counties. According to the USGS, Kings County is considered to be the most densely populated county in the Long Island region.

The areawise distribution of the Long Island for the counties are as follows:

Kings County – 71 square miles

Queens County – 109 square miles

Suffolk County – 934 square miles

Nassau County – 291 square miles

The population of Long Island increased exponentially between the 1950s and 1980s. This was due to the rapid growth of the Long Island. One can understand how big Long Island is as it houses over eight million residents.

Consider the following table for the area of Long Island in different units,

Area Of Long Island InArea
Square Kilometers3629
Square Miles1401 

Why Is Long Island So Big?

Colloquially, Long Island is considered to be made of only two counties, i.e., Nassau County and Suffolk County. The truth is otherwise. Long Island is made up of four counties. The other two counties are Kings County and Queens County.

This popular misconception has made people wonder about the area encompassed by Long Island. When all the four counties are considered, Long Island is 3,629 square kilometers. Additionally, there are a few smaller islands around Long Island which increase its area.

One reason for Long Island is so large is mainly due to many geological processes that occurred over millions of years. The last major change to the topography of Long Island is its glacial history. 

Another reason for the formation of Long Island is coastal erosion that has occurred over millions of years. This has caused Long Island to have the shape of fish.

It is predicted that the northern and the middle part of Long Island was shaped in their present form due to a glacier that occupied the northern part about 22,000 years ago for the next two thousand years.

This phenomenon has not only influenced the area of Long Island but also greatly influenced the topography of the northern and southern parts of Long Island. This is also the primary reason behind the difference in the fertility of its northern and southern parts.

Many more changes in the landmass of Long Island took place due to the Wisconsin glaciation. Other changes occurred due to natural disasters like storms, hurricanes, etc. The last major change is estimated to have been happened around 11,000 years ago.


Most of the outsiders are confused about the area of Long Island as it is quite well connected to the US mainland. As people consider only Nassau and Suffolk counties as a part of Long Island, many consider it to be smaller in size.

Irrespective of many misconceptions and colloquialism, Long Island is very large. It is the eleventh largest island in the US, and it is bigger than the US state of Rhode Island.


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Hi! I'm Nidhi.

Here at the EHL, it's all about delicious, easy recipes for casual entertaining. So come and join me at the beach, relax and enjoy the food.

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