Compared to the other cities in New Jersey and cities in all other U.S. states, how safe is Plainfield, NJ? From the gauges displayed above, you will notice that Plainfield, NJ has been ranked safer than 7% of other cities in the state of New Jersey. In addition, Plainfield, NJ is safer than 16% of cities in the entire United States. To achieve these results, all New Jersey and United States cities were analyzed to determine how many locations had a lower crime rate than Plainfield, NJ. By studying this data, it was possible to determine that Plainfield, NJ is below average in safety when compared with other United States cities.