West Side Story would have looked around and probably picked up an interim booking or something else would have closed. Also at some point West Side Story played the Alvin.
Until about 1970 it was proportionately much cheaper to move a show and also much easier technically. Moves could be done in 2 days with planning.
For instance: Annie played 2 interim bookings (the Anta and the O'Neill) after it was booked out of the Alvin and before the Gershwin opened up; Purlie played the Winter Garden for 3 months between the Broadway and the Anta; My Fair Lady had at least one interim between the Hellinger and the Broadway.
Purlie opened in March 1970 as an interim booking. The Broadway had been promised to Gantry which had a deal to move in April from the Abbott/54th Street because they had to vacate since it was being torn down. Purlie would have had to scramble for a house somewhere, but Gantry flopped out, and Purlie turned out to be a sleeper.
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