Portable restrooms (toilet units) have been used since the 1940s, gaining in popularity and demand during the height of World War II. The earliest units were constructed out of wood and metal, and were needed to provide sanitation services to meet the needs of rapidly constructed military bases, industrial operations that were booming, and support similar activities associated with the rapid movement of people into areas where sanitation services and infrastructure was inadequate.
The post-war building boom that rapidly spread across America, and the growing expectations of a traveling public, provided the tail wind for industry growth over the next twenty years. By the late 1960s, the portable sanitation industry was well established as basic equipment had evolved and people had come to expect better sanitation options wherever they went.
In fact, construction sites, parks, residential home building and special event venues are all expected, and now legislated, to have portable restrooms on site.
By the early 1990s, after many years of invention, innovation and perfection, portable restrooms became more commonplace than ever before and the marketplace begin introducing new offerings such as flushing units, multi-stall restroom trailers, hand washing stations, portable water systems, and more.
Note: Some information provided by PSAI - Portable Sanitation Association International