Losses covered by federally subsidized U.S. crop insurance have declined substantially in the last three years. See table, and maps of indemnities by county:
Crop insurance indemnities, 2014 crop year, by county, for Excess Moisture/Precip/Rain and Drought, when these two causes were both present, and one cause constituted a fifth or more of indemnities for both causes.
Indemnities per acre of cropland, 2016 crop year. Acreage figures (not shown) are from FSA county data, which includes cropland, pasture, and rangeland.
Indemnities per acre of corn, 2016 crop year. Acreage figures (not shown) are from FSA county data.
With crop insurance, as with any data set, looking at the data is a good way of learning about its particulars if not its intentions. (See my Jupyter notebook for assembling the above datasets here.) Some knowledge of the context or domain of the data is usually required.
For background on federal crop insurance, the following may be a start:
Dennis Shields' 2015 report from the Congressional Research Service: https://fas.org/sgp/crs/misc/R40532.pdf
Environmental Working Group's material on crop insurance, which includes interactive maps showing rate of return (payouts compared to premiums) on some crops by county from 2001 through 2014: http://www.ewg.org/research/crop-insurance-lottery. The average federal subsidy for crop insurance premiums is about 60%.
The Natural Resources Defense Council has a 2013 paper on crop insurance, https://www.nrdc.org/sites/default/files/soil-matters-IP.pdf. This paper suggests that crop insurance could be reformed to reward farming that is low risk with environmental rewards.
These estimates were generated via tillage and crop data according to methods detailed here:
Soil Carbon Coalition is a 501(c)3 nonprofit organization