Article Figures & Data
Figures
- Figure 1
100-Mile-Wide Shelterbelt Zone and Counties in the Sample
Source: U.S. Forest Service, digitized from Droze (1977).
- Figure 2
Pretreatment Trends for Revenues per Acre
Note: The gray bars in the graphs mark the implementation of the Great Plains Shelterbelt Project.
Tables
More Treated Less (or Not) Treated Proportion within the
100-Mile-Wide Shelterbelt
Zone >50%Proportion within the
100-Mile-Wide Shelterbelt
Zone <50%Variablesa Obs. Mean S.D. Obs. Mean S.D. Difference Proportion protected by shelterbelts 117 0.30 0.28 117 0.19 0.28 0.11* Other Right-Hand-Side Variables Proportion medium-erodedb 117 0.41 0.35 117 0.38 0.35 0.03 Proportion high-erodedb 117 0.20 0.32 117 0.13 0.26 0.07 Proportion above the Ogallala Aquiferb 117 0.32 0.42 117 0.37 0.45 -0.05 Total precipitation in recent 2 years (mm) 117 1,114.28 166.05 117 1,118.22 239.92 −3.94 Average temperature in recent 2 years (°C) 117 10.51 4.35 117 9.82 3.99 0.69 Farmland/county area 117 0.91 0.07 117 0.89 0.09 0.02 Woodland/county area 117 0.01 0.02 117 0.02 0.04 −0.01 Cropland/farmland 117 0.58 0.17 117 0.57 0.18 0.00 Population per 1,000 acres 117 21.22 11.38 117 26.15 29.24 −4.93 Fraction of rural population 117 0.90 0.16 117 0.86 0.22 0.04 Fraction of farming population 117 0.62 0.11 117 0.58 0.16 0.04* Number of farms/1,000 acres 117 2.64 1.23 117 2.63 1.50 0.01 Average farm size (in acres) 117 443.19 323.11 117 508.53 460.90 −65.33 Area of corn/cropland 117 0.17 0.19 117 0.17 0.17 0.00 Area of wheat/cropland 117 0.29 0.27 117 0.31 0.24 −0.02 Area of hay/cropland 117 0.11 0.13 117 0.13 0.14 −0.02 Area of cotton/cropland 117 0.12 0.25 117 0.05 0.15 0.07* Area of oat, barley, and rye/cropland 117 0.12 0.12 117 0.15 0.12 −0.03* Number of cows/1,000 acres 117 52.24 17.45 117 53.83 23.79 −1.60 Number of pigs/1,000 acres 117 52.38 63.31 117 57.40 76.20 −5.03 Number of chickens/1,000 acres 117 241.55 159.19 117 245.50 189.27 −3.95 ↵a Main data source from the U.S. Department of Agriculture Census of Agriculture and Population; see Appendix B for more detailed definition of variables
↵b Soil erosion data from Hornbeck (2012); data on the Ogallala Aquifer from Hornbeck and Keskin (2014)
↵* t-test with p-value < 0.05
Variables Cropland / (Cropland+ Pasture)
(1)log(Revenue from Crops / Farmland)
(2)log(Revenue from Animal Products / Farmland)
(3)log(Total Revenue / Farmland)
(4)First Stage: Proportion Protected by shelterbelts
(5)Prop. protected by shelterbelts* −0.0156 −0.819*** 0.135 0.569*** 1945-1950 (0.0330) (0.270) (0.176) (0.180) 1954-1959 −0.131***
(0.0476)−1.196***
(0.381)0.689**
(0.301)−0.487**
(0.206)1964-1969 −0.245***
(0.0625)−1.038***
(0.365)0.986**
(0.417)0.0246
(0.252)1978-1982 −0.318***
(0.0779)−0.736*
(0.384)1.312**
(0.579)0.472
(0.364)1987-1992 −0.287***
(0.0726)−0.587
(0.398)1.317**
(0.642)0.533
(0.411)Prop. in the shelterbelt zone*
Each post year0.170***
(0.037)Year and county dummies Yes Yes Yes Yes Yes Outcome variables in 1910-1930a Yes Yes Yes Yes Yes Other control variablesb Yes Yes Yes Yes Yes Erosion from the Dust Bowlb Yes Yes Yes Yes Yes Prop. above the Ogallala Aquiferb Yes Yes Yes Yes Yes Observations 2,433 2,568 2,568 2,574 2,574 Number of counties 234 234 234 234 234 R-squared 0.320 0.945 0.945 0.961 0.713 ↵a Data from 1910 and 1920 are missing in column 1 because the area of cropland and pasture is not reported.
↵b “Other control variables“ include rainfall and temperature for each year and all the other variables listed in Table 1 from 1910–1930; “Erosion from the Dust Bowl” from Hornbeck (2012) include proportions of high- and medium-eroded as in Table 1; “Proportion above the Ogallala Aquifer” is from Hornbeck and Keskin (2014). All these variables are time invariant and all interacted with year-dummies. Standard errors clustered at county level in parentheses
↵*** p < 0.01
↵** p < 0.05
↵* p < 0.1
Variables log(Yield of
Wheat / Acre)
(1)log(Yield of
Corn / Acre)
(2)log(Yield of
Hays / Acre)
(3)log(Irrigated
Acreage)
(4)log(Revenue from
Crops / Cropland)
(5)Prop. protected by shelterbelts* −1.147*** −0.448** 0.407 −5.213** −0.748*** 1945-1950 (0.350) (0.204) (0.438) (2.437) (0.283) 1954-1959 −1.132** (0.499) −0.256 (0.298) −0.380 (0.273) −3.572* (1.830) −1.377*** (0.435) 1964-1969 −0.422 (0.356) −0.705* (0.412) −0.104 (0.216) −5.867*** (2.144) −0.941*** (0.313) 1978-1982 0.0558 (0.264) −0.515** (0.232) −0.128 (0.189) −1.938 (1.770) −0.321 (0.298) 1987-1992 0.203 (0.233) −0.0711 (0.253) −0.102 (0.197) −1.425 (1.622) −0.0130 (0.290) Year and county dummies Yes Yes Yes Yes Yes Outcome variables in 1910-1930 Yes Yes Yes Yes Yes Other control variablesa Yes Yes Yes Yes Yes Erosion from the Dust Bowla Yes Yes Yes Yes Yes Proportion above the Ogallala Aquifera Yes Yes Yes Yes Yes Observations 2,411 2,122 2,326 2,264 2,427 Number of counties 222 233 233 234 234 R-squared 0.904 0.934 0.918 0.832 0.937 Note: Yield of corn in column 2 is missing for 1969 and 1974; yield of all hays in column 3 is missing for 1945; irrigated acreage in columns 4 is also missing for 1945 with its baseline year 1935 (1930 for other variables).
↵a “Other control variables” include rainfall and temperature for each year and all the other variables listed in Table 1 from 1910–1930; “Erosion from the Dust Bowl” from Hornbeck (2012) include proportions of high- and medium-eroded as in Table 1; “Proportion above the Ogallala Aquifer” is from Hornbeck and Keskin (2014). All these variables are time invariant and all interacted with year-dummies. Standard errors clustered at county level in parentheses:
↵*** p < 0.01
↵** p < 0.05
↵* p < 0.1
Variables log(No. of
Cattle/Acre)
(1)log(No. of
Pigs/Acre)
(2)log(No. of
Chickens/Acre)
(3)log(Expenditure
on Feed)
(4)log(Revenue
from Animal
Products/Pasture)
(5)Proportion protected by shelterbelts* 0.197 −0.318 0.0576 0.173 1945-1950 (0.122) (0.196) (0.175) (0.211) 1954-1959 0.562*** (0.187) −0.137 (0.243) −0.0726 (0.270) 0.573** (0.290) 1964-1969 0.854*** (0.249) −0.283 (0.346) 0.588 (0.544) 0.523 (0.537) 0.655* (0.363) 1978-1982 0.855*** (0.294) −0.729* (0.440) 1.190 (1.115) 0.660 (0.595) 0.725 (0.554) 1987-1992 1.004*** (0.352) −0.803 (0.522) 0.987 (1.162) 0.776 (0.646) 0.783 (0.611) Year and county dummies Yes Yes Yes Yes Yes Outcome variables in 1910-1930 Yes Yes Yes Yes Yes Other control variablesa Yes Yes Yes Yes Yes Erosion from the Dust Bowla Yes Yes Yes Yes Yes Proportion above the Ogallala
AquiferaYes Yes Yes Yes Yes Observations 2,574 2,547 2,400 1,628 2,568 Number of counties 234 234 234 234 234 R-squared 0.702 0.972 0.934 0.902 0.940 note: Yield of corn in column 2 is missing for 1969 and 1974; yield of all hays in column 3 is missing for 1945; irrigated acreage in columns 4 is also missing for 1945 with its baseline year 1935 (1930 for other variables)
↵a “Other control variables” include rainfall and temperature for each year and all the other variables listed in Table 1 from 1910–1930; “Erosion from the Dust Bowl” from Hornbeck (2012) include proportions of high- and medium-eroded as in Table 1; “Proportion above the Ogallala Aquifer” is from Hornbeck and Keskin (2014). All these variables are time invariant and all interacted with year-dummies. Standard errors clustered at county level in parentheses:
↵*** p < 0.01
↵** p < 0.05
↵* p < 0.1
Eastern Half of the Counties Western Half of the Counties Cropland /
(Cropland+
Pasture)
(1)log(Revenue
from Crops/
Farmland)
(2)log(Revenue from
Animal Products/
Farmland)
(3)log(Irrigated
Acreage)
(4)Cropland /
(Cropland+
Pasture)
(5)log(Revenue
from Crops/
Farmland)
(6)log(Revenue from
Animal Products/
Farmland)
(7)log(Irrigated
Acreage)
(8)Panel A: First Stage Proportion in the shelterbelt zone
Each post year*0.260**
(0.100)0.137***
(0.044)Panel B: Second Stage Proportion protected by shelterbelts* −0.0216 0.0536 0.0576 0.128 −0.130 −2.011*** 0.948 −12.75 1945-1950 (0.0246) (0.275) (0.142) (2.037) (0.131) (0.775) (0.680) (9.207) 1954-1959 −0.0921**
(0.0387)0.442 (0.375) 0.617**
(0.269)1.261
(2.112)−0.225
(0.163)−2.686**
(1.181)2.533**
(1.160)−9.994*
(5.960)1964-1969 −0.124**
(0.0507)0.604
(0.388)0.988**
(0.392)0.298
(2.355)−0.310*
(0.179)−1.947**
(0.948)2.487*
(1.462)−10.26*
(5.876)1978-1982 −0.109*
(0.0606)1.058**
(0.536)1.764***
(0.574)−0.134
(1.449)−0.288
(0.188)−1.595*
(0.966)3.614*
(2.168)1987-1992 −0.147**
(0.0706)1.262**
(0.537)1.505***
(0.529)−0.596
(1.517)−0.358*
(0.211)−1.838*
(0.991)3.217
(2.251)0.347
(2.016)Year and county dummies Yes Yes Yes Yes Yes Yes Yes Yes Outcome variables in 1910-1930a Yes Yes Yes Yes Yes Yes Yes Yes Other control variablesb Yes Yes Yes Yes Yes Yes Yes Yes Erosion from the Dust Bowlb Yes Yes Yes Yes Yes Yes Yes Yes Proportion above the Ogallala Aquiferb Yes Yes Yes Yes Yes Yes Yes Yes Observations 1,243 1,263 1,263 1,110 1,190 1,305 1,305 1,035 Number of counties 115 115 115 115 119 119 119 119 R-squared 0.762 0.964 0.957 0.957 0.734 0.950 0.945 0.945 ↵a Data from 1910 and 1920 are missing in column 1 because the area of cropland and pasture is not reported.
↵b “Other control variables“ include rainfall and temperature for each year and all the other variables listed in Table 1 from 1910–1930; “Erosion from the Dust Bowl” from Hornbeck (2012) include proportions of high- and medium-eroded as in Table 1; ”Proportion above the Ogallala Aquifer” is from Hornbeck and Keskin (2014). All these variables are time invariant and all interacted with year-dummies. Standard errors clustered at county level in parentheses
↵*** p < 0.01
↵** p < 0.05
↵* p < 0.1
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