In Rebecca Gilman’s 2022 play “Swing State,” a grief-stricken widow mourns the loss of the insect, plant and animal species that once thrived on her 48 acres of grassland in the American heartland. But the declining population of sparrows, seeds, butterflies and wildflowers that Peg has long treasured are just part of the increasingly bleak situation in her rural Wisconsin community. Herbicides are poisoning the groundwater, young people are overdosing on fentanyl-laced...