Theories range from design faults and construction errors to a rush to finish the job and budget constraints.

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Thousands of workers and volunteers have been working to finish construction for Monday's celebrations, with white tents, trailers and generators being set up along the Washington Mall's parade route as nearby buildings were adorned with red, white and blue bunting.

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The venture has scheduled construction of a plant in Hangzhou, China, to dye and finish interior fabrics.

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