What Is Nantucket's Actual Population? Town Seeks To Answer An Elusive Question

What is Nantucket’s population? It's a much-debated question, yet one with elusive answers. But we may soon have a better idea.

The Select Board has approved about $45,000 for a UMass Amherst study to determine the island’s population in the off-season, the summer, and the shoulder seasons.

“From my perspective in the food security world, being able to quantify our population to understand what social services needs are as well is going to be really helpful,” Select Board member Brooke Mohr said.

The census estimates Nantucket’s population at around 15,000, but that figure is widely believed to be an undercount. In 2020, island demographer Peter Morrison estimated the island’s year-round population at just over 17,000. The number has likely grown since then.

The new study will use the census data, but also plans to incorporate data from an array of other sources, including the Nantucket assessor’s records and water, sewer, and travel data, to build a more complete picture of the island’s population.

“It’s really important for long-range planning and knowing how many people are here,” Planning & Lane Use Services director Leslie Snell said.

The UMass Amherst study will also look at Nantucket’s summer population. In 2022, the Nantucket Data Platform suggested that figure had grown rapidly over the last few years, ballooning to an average of 58,000 and a peak of over 65,000. Some sources, including the town, put that summer peak far higher, at closer to 80,000.

“A lot of numbers are floated,” Snell said. “Anything from 50,000 people to 100,000 people, and that’s a really big gap, so I think it’s important that we have a reputable, unbiased source.”

Since 2022, the data on whether Nantucket’s summer population has been growing have been more mixed. The UMass study could provide some clarity on the island’s summer population, and would also give one of the first looks at Nantucket’s population during the shoulder season.

“Nantucket County experiences dramatic seasonal population swings that are not captured by official U.S. Census Bureau population counts, which only enumerate year-round residents,” a pre-scope document obtained by the Current reads in part. “To effectively guide policy, manage infrastructure, and provide appropriate levels of service, the Nantucket Planning & Economic Development Commission requires a comprehensive estimate of its effective population -- the actual number of people present on the island at various points throughout the year.”