But in rural Nebraska, politics can be taboo in polite conversation, and the publicity has had drawbacks. Jenni Harrington said her children had been teased at school about her activism. When she installed a giant yard sign last year supporting Dave Domina, the anti-pipeline Democrat running for the United States Senate, a neighbor countered with an equally large tribute to the pro-pipeline Republican and eventual victor, Ben Sasse.

Still, the efforts of the Harringtons and their allies have resounded far beyond the Nebraska farmland, and national environmental groups have joined forces with an unlikely, and bipartisan, team of farmers, ranchers and city dwellers. The pipeline has also become a favored cause of some Republicans nationally, who say the project would bring needed energy from an allied nation at minimal risk.

TransCanada officials insist the pipeline is safe and note that they shifted the route through Nebraska because of ecological concerns. That revised path won the blessing of the governor then, Dave Heineman, and a State Supreme Court ruling this month allowed his approval to stand.

Image Opposition to and support for the Keystone XL project are evident in landowners’ signs, like this one near Bradshaw. Credit... Andrew Dickinson for The New York Times

But the pipeline’s prognosis here is complex. Four of seven justices on the Nebraska Supreme Court ruled that the law giving Mr. Heineman the authority to sign off on the route was unconstitutional. The other three justices did not say whether they thought the measure was constitutional, and the law stood because five votes were needed for it to be overturned.