Early this spring I spread leaves down one garden path and left an adjacent path unmulched.
As I write now, the differences between the two paths couldn't be more striking: The leaf-covered path is virtually free of weeds, while the once plain-earth path is a mass of weeds and grass. Both paths were deliberately not weeded during the season to test the effectiveness of the leaf mulch.
While all but eliminating weeds from the path during the season, and keeping my shoes free of mud whenever it rained (although, much to my wife's dismay, I occasionally brought wet, clinging leaves into the house), the leaves have also done something else for me.
What had once been 4 to 6 inches of leaves at the beginning of the season is now a thin layer of rich, black humus with a paper-thin covering of undecomposed leaves.
One of the fall tasks in my garden is to scrape this newly acquired topsoil from the garden paths and sprinkle it over the raised vegetable beds, where it will help along next year's crops.
I do this by raking the paths vigorously to disturb the soil, then spading the loosened soil onto the beds. As a result, fewer earthworms are injured.
Meanwhile, fall's new crop of leaves will be spread over the paths to repeat the weed-defeating, soil-building program. I walk over the leaves after first spreading them to tramp them down and reduce the possibility of their being blown around. In the narrow paths between the raised beds I have little trouble with the wind, however, and the first good fall rain ends the problem permanently.
I mention this now because the leaf-collecting season will soon arrive in earnest. Take advantage of it; grab as many leaves as you can from under your own trees and from those of your neighbors as well.
In my area I collect leaves that are conveniently bagged for the garbage trucks. I store a large quantity in a fenced-in enclosure for use the following year as mulch and in composting; the rest go in the paths between the raised beds.
Wood chips are also excellent on garden paths. They, too, rot down, but much more slowly than leaves.
Rake off the undecomposed chips before scraping up the humus for your garden; then return the old chips to the path, along with some new ones.