When industry pioneer Philip Ilsley built the first gunite pool in 1940, he couldn’t have known that within four years a post-war economic boom would put the largest U.S. middle class in history at the feet of the new pool-construction industry.

Ilsley, who by this time owned Paddock Pools, shot the first gunite pool, which he called the “people’s pool,” in west Los Angeles, incorporating his inverted-dome shape. It measured 17 by 34 feet and cost between $1,000 and $1,600 — somewhere between one-fifth and one-half the cost of the poured-concrete pools his company had produced until then. The new method proved not only more cost effective than poured concrete, but also easier to control than hand-packed concrete, which couldn’t hold its shape on vertical walls and so required a very gradual slant from wall to floor.

Paddock’s productivity immediately jumped — from about 40 pools a year to 226. The volume business had begun.

Some of Paddock’s construction workers hated the new process, reportedly even sabotaging one job so badly that Ilsley had to modify it on site. He put large rocks at the water’s edge and extra guniting to accentuate its irregularities. It became the first gunite mountain-lake pool.

The pool industry may have remained lucrative through the Depression, but World War II sent it into virtual hibernation. Considering pools a non-essential use of scarce materials, the government banned most construction.

Once the war was over, however, millions of men who were trained to swim and financially fortified by the GI Bill could own homes and enjoy new comforts. Some wives continued to work after the war ended, boosting the family income even higher. These events couldn’t have been better timed if Ilsley himself had orchestrated them.

Materials remained scarce immediately after the war, but the industry began laying the groundwork for its first true building boom with early public relations efforts that convinced publications to run stories about pools.

In 1946, Phil Anthony turned his attention from building backyard concrete-block incinerators to pools exclusively, forming Anthony Pools in Los Angeles. Soon after, in 1948, Herman Silverman started Sylvan Pools. In 1952, California Pools opened its doors for business.

After another industry stall during the Korean War, the construction boom was cemented in place as 1952 to ’57 brought the first true rush for pools. By this time, the pool industry had begun moving inward from the two coasts, with Florida, Texas and the upper Midwest taking their cues from California and New York. In this decade, Anthony Pools — now a multi-branch company — brought financing to the industry, prompting even more families to call local pool builders. The National Swimming Pool Institute formed in 1956, coalescing the industry and providing a forum for builders and manufacturers to exchange ideas and solutions.

As the market for pools thrived, it brought some unfortunate byproducts, namely, price competition and the resulting corner-cutting, fly-by-night operations and even false advertising.

The ’50s boom continued through the 1960s, with burgeoning businesses, low unemployment and foreign markets clamoring for American products. Motels and publications continued to put pools in people’s consciousness, and housing contractors began including pools in their tract plans.

From the end of World War II through the 1960s, the gunite pool and many of its components went from invention to fine-  tuning, until they emerged very similar to what we see on modern pools today.

Many companies didn’t convert to gunite until the 1950s, with the East Coast’s first builder, E.L. Wagner Co. of New York, shooting for the first time in 1950. Anthony Pools started guniting in ’51. While gunite made the most sense for residential pools, this new process required a substantial up-front investment in machinery. And the pools were still more labor-intensive and rudimentary than modern gunite models.

Builders continued to experiment with new types of pool structures, some less successful than others. Some builders, before they converted to gunite, used tar to seal control joints, which made painting them impossible. Others reportedly experimented with urethane and even roofing paper.

During this period, crews’ lives were simplified as excavation equipment shrank and became easier to maneuver; rebar lost the hard spots that would kink and refuse to bend; and manufacturers produced guniting equipment that didn’t require a dedicated operator.

Pool systems built in the 1960s could more gracefully withstand time and usage, thanks to plumbing’s evolution from galvanized iron and copper to black polyethylene, and finally to PVC. Fittings also went from brass to stainless steel to plastics.

Hydraulic systems became more effective as builders included main drains as standard components (but usually just one per residential pool). When manufacturers began making the drains as a complete unit, builders no longer had to cut them into gunite, cover them with a grate and hope they wouldn’t leak.

Skimmers came into existence as well, first as a floating device and later as part of the pool wall. Underwater lights fell into wide acceptance too, once people got used to the idea of having electricity near the water. Ground fault circuit interrupters entered the scene in this period as well, helping to quell fears.

Builders made pool configurations more interesting and user friendly by fashioning the kidney-shaped pool — the ’50s and ’60s version of the freeform — and designing love seats and steps. The use of marble dust instead of silica sand in plaster eliminated the tan-colored spots that would appear over time.

Otherwise, the appearance of pools remained relatively static during these 30 years. For the most part, builders had only blue and white tiles at their disposal, and decks remained mostly of broom-finished or salt-finished concrete, although less-accessible native stones and exposed aggregate did cover decks on high-end projects. In 1962, the advent of Kool Deck ushered in the modern deck finishes we see today. And cantilevered decks began appearing in the mid- to late-’60s.