Recycling continues to confuse us.

For a progressive city with a nation-leading climate plan and a love of the outdoors — and a place where half of all households have signed up for the city composting pickup — you'd think Minneapolis residents would know that, for example, aluminum cans should go in the blue recycling bin.

But, more than 120 years after America's first aluminum recycling plant was built, about half of aluminum cans in Minneapolis homes are being recycled. The other half is being thrown in the garbage.

Meanwhile, large amounts of detritus that can't be practically recycled, notably certain plastic materials, are being wishfully pitched in blue bins, contaminating the recycling stream and costing money for it to be removed later.

About 13% of Minneapolis' garbage contains things that could be recycled.

On the whole, residents are doing a "relatively good job," but there are "a lot of opportunities for improvement," according to the most recent city analysis of residential refuse. If you're confused (and who isn't?) about what goes where, the city has guides online.

How they did it: A team of city officials scoured everything in the garbage, recycling and, where applicable, composting bins of 700 randomly selected, single-family homes. Here's what they found:

Top recyclables in garbage

Metal: The estimated 440 tons of aluminum cans thrown in the trash annually could be sold on the recycling market for $590,000. Other recyclable aluminum being tossed away — aluminum foils and trays, for example — could fetch $260,000. But it's not just aluminum cans. Only 29% of steel cans, such as canned foods, are being recycled.

  • Tip: As long as you rinse out the food, all these cans can be put in the blue bin. But cans that held paint, gas or hazardous materials must be dropped off at a hazardous waste site.

Paper and cardboard: The vast majority of people who still get newspapers are recycling them, but there's other paper that's being pitched. Much of it comes in the form of stiff, often brown paper found in packaging. The cardboard from those Amazon deliveries can also be recycled, but it looks like only 54% of it is. By volume, about half of everything in the city's recycling bins is paper and cardboard, but city officials believe only about half of all the recyclable paper and cardboard in our homes is being recycled.

  • Tip: Pizza boxes can now be recycled, as long as there's not too much food and grease. Got a greasy, cheesy box? Remove the (usually clean) top and recycle that.

#1 plastic: Your basic plastic bottles for water, flavored drinks, salad dressing and other foods can be recycled, but only about 42% of it is. The rest, valued at around $200,000 annually, is being pitched. As long as you clean out the food — even peanut butter jars can be cleaned well enough with soap and water — this ubiquitous transparent plastic can be recycled into new bottles or clothes.

  • Tip: Don't crush the bottle or it might slip through the sorting equipment at the recycling center. Screw the cap on because it will slip through otherwise.

Top 'wish-cycling' sins

Wrong plastic: Minneapolitans have gotten a lot better at not putting plastic bags in the recycling. But the largest share of stuff we incorrectly toss into recycling bins is plastic.

It's not that these plastics can't be recycled at all; some of them can, but the equipment used to sort through everything can't handle it. Plastic film, bubble wrap and anything smaller than 3 inches won't work.

  • Tip: Nearly 12% of recycling contamination is plastic cutlery and straws. Consider asking for them to be left out of your to-go order.

Wrong paper: Tissues and napkins — even those that have never come into contact with food or germs — can't go in to the blue bin. Neither can paper cups and to-go containers. It adds up to more than 19% of recycling contamination.

  • Tip: Most of these paper products can be composted via the city's pickup or drop-off services. Look into it.

Food: The yogurt tub can be recycled, but not the yogurt. More than 18% of recycling contamination is food that should have been scraped or rinsed. Food should go in the garbage or the composting bin, if you have one.

Correction: An earlier version of this story mischaracterized recycling contamination. About 41% of items mistakenly put in recycling bins are plastics.