The following information is from the Suffolk County Board of Elections. Shelter Island will not have an early voting site, but you may vote at any of the listed locations on the BOE website. They include one in Mattituck, Southampton and East Hampton.

2020 Early Voting FAQ
2020 General Election – November 3, 2020
What is Early Voting?
Early voting is a nine (9) day period where voters can vote in-person before Election
Day in their county.
Who can vote early?
All registered voters can vote early.
When can I vote early?
Early Voting in New York State will begin prior to the November 3rd General
Election. The early voting period will be from: Saturday, October 24, 2020 through
Sunday, November 1, 2020.
Where can I vote early?
You can vote in an early voting center in Suffolk County – at any of the 12
locations. See a list of the 2020 General early voting sites at
https://suffolkcountyny.gov/Departments/BOE/Early-Voting-Sites-11-3-2020 .
How will I vote during early voting?
Voting during early voting is the same as voting on Election Day. When you get to the
early voting center, you will check in to vote, receive your ballot and vote as any other
election.
There will be instructions available at the early voting centers to familiarize you with the
ballot. There will also be a notice to voter and bill of rights. You may ask an election
inspector to explain how to vote, or if you need any assistance.
If you vote during the early voting period, you are not eligible to vote on Election Day.
When will early voting results be posted?
Early voting votes will be canvassed and reported after 9pm on Tuesday, November 3,
2020 and the unofficial results will be posted on the Suffolk County Board of Elections
website that night.