Petersburg, NE has a population of 345 and is the 21,694th largest city in the United States. The population density is 923 per sq mi which is 3753% higher than the Nebraska average and 919% higher than the national average. The median age in Petersburg is 50 which is approximately 39% higher than the Nebraska average of 36. In Petersburg, 77% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 83% of Petersburg residents were born in Nebraska, 16% were born out of state, 0% were born outside of the United States and 1% were foreign born.