Doesn't matter, the theater straddles the 2 streets and you can come in from either side.
The entrance is open to both sides, W50st. and W51st., you can give 50st-Broadway or 51st-Broadway to a cab driver.
GPS likes 235 West 50th Street which is a delivery address, and the mailing address is 1633 Broadway (theater is at the westernmost end of the building).
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