The Flag of Queens, comprising three horizontal stripes, two azure at the top and bottom, and one argent between them. The colors were inspired by the coat of arms of the Dutch director of the New Netherlands, Willem Kieft. The crown symbolizes that of Catherine of Braganza for whom the borough's name derives, 1898 was the year in which it was incorporated as a borough during the City's consolidation. The wampum ring represents the Lenape people who used to collect the shells to make it on these shores, when the land was known as "Sewanacky", the "island of seashells". The tulip represents the Dutch settlers while the Tudor rose represents the English; the latter often appears erroneously with 4 petals on Borough graphics. 
From the original text documenting the design-


In April, 1913, Mr. G. Howland Leavitt, Chairman of the Rapid Transit Celebration Committee of the Borough of Queens, and Messrs. Louis Windmuller and Charle G. Meye of that committee, in co-operation with the Hon. Maurice E. Connolly, Borough President, and the Queens Borough Chamber of Commerce, invited the co-operation of this Society in designing a flag for the Borough of Queens, to be unfurled during the celebration of the commencement of the work of constructing the dual rapid transit system in that Borough in the following June [1913].


The official description of the flag lacks a proportion however the original artwork (see source) works out to be 4:5, as opposed to later renditions that give the flag a 2:3 proportion; neither of which appears to be codifed.
Own work, rendered from the original 1913 artwork
Simtropolitan, original design by an unknown artist from The American Scenic and Historic Preservation Society