Since the mid-20th Century, advances in rubber, plastics, synthetic cloth, and industrial adhesives have allowed manufacturers to create shoes that stray considerably from traditional crafting techniques. Leather, which had been the primary material in earlier styles, has remained standard in expensive dress shoes, but athletic shoes often have little or no real leather. Soles, which were once laboriously hand-stitched on, are now more often machine stitched or simply glued on. Many of these newer materials, such as rubber and plastics, have made shoes less biodegradable. It is estimated that most mass-produced shoes require 1000 years to degrade in a landfill. In the late 2000s, some shoemakers picked up on the issue and began to produce shoes made entirely from degradable materials, such as the Nike Considered.
Many early natives in North America wore a similar type of footwear, known as the moccasin. These are tight-fitting, soft-soled shoes typically made out of leather or bison hides. Many moccasins were also decorated with various beads and other adornments. Moccasins were not designed to be waterproof, and in wet weather and warm summer months, most Native Americans went barefoot.