Why is Sutherland, Nebraska so murdery?

One episode carries Sutherland's entire count. Episode 194 accounts for all six murders within 25 miles, and all six happened in the village itself, so the ranking of 235th overall and first in Nebraska rests on a single case in October 1975 rather than a run of them down the decades. There is no spread to measure here: one date, six victims, and a lot of empty map around it.

Sutherland is a village of 1.3 square miles in Lincoln County, western central Nebraska, three and a half hours from Lincoln and three hours and forty five minutes from Denver. In 1975 it held roughly 800 to 850 people, mostly ranchers and railroad workers. It was incorporated in 1905, takes its name from a Union Pacific official, and sits alongside the old Mormon, Oregon and Pony Express routes. By 2020 the population was 1,601.

Worth saying plainly: this counts the show's cases, not crime statistics. James and Jimmie choose the towns, and a place of 800 people can top a state's table on the strength of one episode.