Month Million Square Feet 1919-01-01 8.60000 1919-02-01 8.50000 1919-03-01 13.1000 1919-04-01 19.0000 1919-05-01 24.5000 1919-06-01 35.0000 1919-07-01 35.4000 1919-08-01 35.5000 1919-09-01 28.0000 1919-10-01 40.6000 1919-11-01 33.6000 1919-12-01 33.6000 1920-01-01 30.3000 1920-02-01 25.2000 1920-03-01 38.6000 1920-04-01 30.3000 1920-05-01 25.0000 1920-06-01 26.0000 1920-07-01 19.4000 1920-08-01 17.2000 1920-09-01 18.1000 1920-10-01 14.1000 1920-11-01 11.5000 1920-12-01 8.20000 1921-01-01 8.70000 1921-02-01 8.30000 1921-03-01 12.3000 1921-04-01 16.5000 1921-05-01 16.6000 1921-06-01 16.9000 1921-07-01 17.6000 1921-08-01 17.1000 1921-09-01 19.9000 1921-10-01 18.4000 1921-11-01 14.8000 1921-12-01 13.0000 1922-01-01 11.9000 1922-02-01 13.4000 1922-03-01 21.4000 1922-04-01 26.1000 1922-05-01 27.9000 1922-06-01 28.9000 1922-07-01 27.2000 1922-08-01 29.2000 1922-09-01 20.4000 1922-10-01 20.8000 1922-11-01 17.9000 1922-12-01 13.5000 1923-01-01 13.7000 1923-02-01 18.4000 1923-03-01 25.3000 1923-04-01 26.0000 1923-05-01 25.7000 1923-06-01 20.4000 1923-07-01 18.1000 1923-08-01 15.5000 1923-09-01 16.4000 1923-10-01 18.9000 1923-11-01 17.9000 1923-12-01 17.3000 1924-01-01 14.2000 1924-02-01 19.6000 1924-03-01 23.7000 1924-04-01 20.7000 1924-05-01 22.8000 1924-06-01 18.8000 1924-07-01 18.2000 1924-08-01 17.0000 1924-09-01 18.9000 1924-10-01 18.8000 1924-11-01 17.0000 1924-12-01 17.0000 1925-01-01 18.1000 1925-02-01 14.2000 1925-03-01 23.8000 1925-04-01 25.9000 1925-05-01 26.0000 1925-06-01 28.6000 1925-07-01 27.0000 1925-08-01 30.7000 1925-09-01 29.6000 1925-10-01 23.3000 1925-11-01 22.0000 1925-12-01 20.3000