Delaney Hall

Unlike San Francisco, there are places where the more trash cans equals less litter equation seems to be true.

Rachel may not have a definitive answer about what's going on in San Francisco, but she does have some theories.

For one, the city has a higher than average unhoused population.

And sometimes people sort through public trash cans for valuable recyclables and then leave trash scattered on the ground.

Then there's illegal dumping, which is a huge part of the equation.

About 18,000 tons of trash get dumped on San Francisco streets every year.

This is stuff like mattresses, furniture, construction debris and bags of garbage.

Public Works actually has a team of investigators who go out and rip open trash bags looking for addresses and shipping labels to figure out who's responsible.

On top of that, there have been complaints about a scandal-plagued company called Recology, which the city has hired to empty the trash cans on a daily basis.

Some people complain that Recology does not empty them enough.

Anyway, for whatever reason, there's litter.

And when it comes to littering, studies show that people take their cues from their environment.

When a space looks clean, they tend to keep it clean.

But when it's already dirty, they feel more comfortable adding to the mess.

And so, in a place like San Francisco, it can become a self-reinforcing cycle of trash leading to more trash.

Which brings us back to the trash can pilot in the Mission District.

Adding cans didn't really seem to help with the litter, and so Public Works decided to run a different experiment.

They wondered, what if instead of putting out more trash cans, they redesigned them?

Their old models, known as the Renaissance cans, had been on the streets since 1993, and they were reaching the end of their natural lifespan.

So it was time for new cans.