Not to be that guy all the time, but litter and dirty city streets is a major issue in almost every major US city. You can google litter and enter any major city and read article upon article about how dirty said city is. Its just such a big and complex issue. For one, cities are usually super dense which usually means more trash and more trash usually means more of it will overflow causing the issue. Another reason is that cities in the US usually take out the garbage in big plastic bags and leave it on the sidewalk on trash day which allows the homeless and animals to pick at it. Another reason is that US cities have been conditioned to not spend money on major infrastructure projects that would seriously tackle the issue. For example, in Europe, cities have long gone for placing trash underground where it would be collected at a later date. That costs a shit ton of cash to retrofit cities with that, but lead to healthier environments.... in the US, since the 70s, policy has turned from spending money on internal issues to basically leaving cities to fend for themselves which pushed cities to rely on major credit bureau to help them invest in major projects (this is why a city's Moody score is so important as they literally dictate which cities are worthy of investment and which ones are not [basically, if a city uses less of its budget on social services like police, fire department, sanitation, and can balance the budget they are investment worthy]), and that has forced cities to ignore major social issues.

Also, there issue of cycles... if you grew up in a city with trash issues you are more likely to contribute and unfortunately Newark, like many of its siblings, are all suffer from that cycle.