 According to the New York State Department of Transportation ( NYSDOT ) , NY 324 begins at NY 384 in eastern Niagara Falls . NY 324 heads south , overlapping with I @-@ 190 ( the Niagara Section of the New York State Thruway ) across the North Grand Island Bridge to Grand Island , where it leaves the expressway at exit 20 . However , as signed , NY 324 begins at the north end of Grand Island , where it splits off from the Interstate Highway as Grand Island Boulevard . South of exit 20 , the official and signed routings are identical . 
