2 Southern California cities top study to find dirtiest in nation

A new assessment to rank the dirtiest cities in America had a field day with Southern California, which took both first and second place while filling four of the top ten spots.

The study conducted by the national lawn care company LawnStarter, analyzed several categories, including cleanliness, pollution, living conditions, waste infrastructure and resident dissatisfaction. 

San Bernardino easily won the title for dirtiest city in both California and the U.S. for the second straight year, with the worst pollution rating and the highest number of dissatisfied residents, according to the study.

Next in line was Los Angeles, which was also joined in the top ten by Ontario (5) and Corona (10).

2025’s Dirtiest Cities in America by LawnStarter:

• 1. San Bernardino, CA (Score: 55.34)
• 2. Los Angeles, CA (Score: 49.79)
• 3. Detroit, MI (Score: 49.72)
• 4. Reading, PA (Score: 49.31)
• 5. Ontario, CA (Score: 48.20)
• 6. Newark, NJ (Score: 48.06)
• 7. Phoenix, AZ (Score: 47.47)
• 8. Jersey City, NJ (Score: 46.53)
• 9. Las Vegas, NV (Score: 45.96)
• 10. Corona, CA (Score: 45.36)

“California has been leading the way in sustainable development, from green lawn care to composting to electric energy and technology. However, earlier this year, the Golden State reversed their ‘clean fleets’ mandate for electric trucks,” the study stated.

Topping the list of cleanest cities was South Bend, IN, with a score of 18.53, followed by Wilmington, NC and Des Moines, IA.