No aspect of housework stood in greater need of motor power than washing clothes, a job so slow and grueling when performed manually that laundresses were by far the most sought-after domestic help. In the preelectric era, Mondays were traditionally devoted to doing the laundry. First, the clothes were rubbed against a washboard in soapy water to remove most of the dirt; next they were wrung out, perhaps by running them through a pair of hand-cranked rollers; they were then boiled briefly in a vat on top of the stove; then, after removal with a stick, they were soaped, rinsed, and wrung out again; finally they were hung on a line to dry—unless it was raining. The arrival of electricity prompted many efforts to mechanize parts of this ordeal. Some early electric washing machines worked by rocking a tub back and forth; others pounded the clothes in a tub with a plunger; still others rubbed them against a washboard. A big improvement came in 1922 when Howard Snyder of the Maytag Company designed a tub with an underwater agitator whose blade forced water through the clothes to get the dirt out.

The following decade saw the introduction of completely automatic washing machines that filled and emptied themselves. Then wringers were rendered unnecessary by perforated tubs that spun rapidly to drive the water out by centrifugal force. An automatic dryer arrived in 1949, and it was soon followed by models that were equipped with sensors that allowed various temperature settings for different fabrics, that measured the moisture in the clothes, and that signaled when the drying job was done.

Like the vacuum cleaner and washing machine, most modern appliances have a long lineage. One, however, seemed to appear out of the blue, serendipitously spawned by the development of radar during World War II. Much of that work focused on a top-secret British innovation called a cavity magnetron, an electronic device that could produce powerful, high-frequency radio waves—microwaves. In 1945 a radar scientist at Raytheon Corporation, Percy Spencer, felt his hand becoming warm as he stood in front of a magnetron, and he also noted that a candy bar in his pocket had softened. He put popcorn kernels close to the device and watched with satisfaction as they popped vigorously. Microwaves, it turned out, are absorbed by water, fats, and sugars, producing heat and rapidly cooking food from the inside. From Spencer's discovery came the microwave oven, first manufactured for commercial use in 1947 and ultimately a fixture in millions of kitchens, although the household versions were not produced until the mid-1960s.