Thanks to the gunite and hand-packing concrete processes, the price of residential swimming pools plummeted between the early-’40s and late-’50s. But they continued to remain out of reach for many homeowners in the Northeast and Midwest, where harsh weather conditions necessitated more expensive construction.

Several pioneering manufacturers reached out to this remaining sector of the middle class by producing and packaging easy-to-install wall systems with all the necessary components. As an added benefit, this method of installation required fewer men and a simpler building process than any inground pool to date.

The first company to offer such a package, Cascade Industries, opened its doors in 1954. The company offered three choices of wall configurations: 12 by 27 feet, 16 by 34 feet and 24 by 40 feet, all with depths starting at 3 feet and sloping down to 5, 7 or 8 feet. The use of concrete blocks for the walls, however, did result in one problem: The blocks could leave the end product as much as 6 inches off the original plans.

At about the same time, Heldor Industries came out with a poured-concrete package pool. Esther Williams Pools was soon to follow in 1956 with its concrete-block package pools.

These early packages did present their share of problems: The filters cost extra, and the fittings and drains used for concrete pools didn’t work. Cascade’s founders soon looked to the boating industry for components that could be adapted to vinyl-liner pools.

Within a few years, Cascade and Esther Williams began offering pools with walls made of a relatively new product: pressure-treated wood. Cascade offered its 16-foot wood-walled model through the Spiegel catalog. The package contained panels, lumber bracing, liner, coping, a tank for filtration, four gate valves, 70 feet of 1-inch pipe and 40 feet of 1-1/4-inch pipe, plus fittings, instructions and a layout kit. It sold for $995.

The floors were finished with sand before crews placed the 20-mil liners over the structure. The coping had no track-and-beading system to hold the liner in place, so builders wrapped the liner around the pool top.

Because builders didn’t have vacuum devices at their disposal to fit the liners in place, they would fill the pool with water, hoping the water pressure would press the vinyl tightly against the walls.

Before long, the industry called for a different material — something lighter that could be easily mass produced, shipped and stored, and would hold up longer in the ground. This led to the development of the steel-walled pool in the early-’60s, with an aluminum version following on its heels. Steel had been used in commercial pools since before World War II, with some panels measuring 1/4-inch thick and welded together at the site. These, too, were concentrated in the eastern half of the country because shipping farther west cost too much.

Working with steel, manufacturers could cut the product to more perfect tolerances and build in ribs and flanges for added strength. However, the steel-manufacturing process limited pool configurations because fabricators had to cut from steel sheets provided by their suppliers.

Early package-pool manufacturers created their industry from scratch, recruiting and training builders on how to sell and install this quick, low-cost alternative to gunite. By 1964, package pools accounted for an estimated 16 percent of U.S. pool sales.

These pools were still primarily rectangular with aqua-colored interiors and white coping. Like their concrete cousins, early package pools had hard, 90-degree corners, making it impossible for a liner to fit snugly, leaving air gaps at the corners and putting extra stress on the liners.

Components didn’t always match perfectly and early braces were not made for easy adjustability, which made it tedious to readjust them if they got thrown out of alignment.

During the ’60s, ’70s and ’80s, manufacturers were able to refine these design quirks. They developed galvanizing and coating methods to protect the steel against deterioration. Wider flanges, more bends and ribbing were added to walls for extra strength along with a prefabricated coping with a bead receptacle for the liner.

Builders began adding concrete collars at the base of the wall system for added permanence. They created “hard bottoms” surfaced with 1 to 2 inches of grout, vermiculite or concrete for more durability. Conversely, some builders softened the walls by adding sheets of foam between the wall and liner.

Initially, concrete pool builders resisted this prefabricated line of products with their softer materials. “When they first came out, we laughed at them,” said Al Rizzo, president of Rizzo Construction Pools in Newington, Conn. “I kept looking at it as something that would just disappear. It would go away. Who would want it? By 1965, I think we did 85 liner pools in one year.”

This stigma took years to eradicate, with major progress made in the 1970s, when package-pool manufacturers began participating in the inner circle of the National Spa & Pool Institute.

In the late-’70s and early-’80s, manufacturers began offering polymer wall assemblies. The lighter material could be molded to any shape, and once consumers overcame their initial resistance (plastic glass, yes; plastic pools, no), they warmed to this shape flexibility. Steel- and aluminum-wall manufacturers had to follow suit, finding ways to offer more shapes themselves.

Later that decade came computer-aided drafting (CAD) to ease the ordering process and yield better-fitting liners. CAD could help builders create any shape of wall system and vinyl liner they could imagine.

Another prefabricated product, fiberglass pools, also began production in earnest in the late-’50s and early-’60s, after a slow start some time in the 1940s. Pascal Paddock is credited with this first fiberglass pool, engineered as a 15-by-30-foot oval that came in four parts that fit together like pie pieces.

Distribution was narrow because of difficulty in shipping and inconsistencies in sealing and color matching.

In the late-’50s, W. R. Chance Co. produced a 15-by-35-foot, one-piece fiberglass pool. In 1958, Family Fun Pools began manufacturing a prefabricated pool made with fiberglass sidewalls and a poured concrete floor. These proved more flexible in size and shape than the one-piece units.

San Juan Pools, which opened its doors in 1958, spent its first two decades selling forms to dealers, who would manufacture the vessels they installed. This changed in the mid-’70s when the manufacturer shifted to the more efficient method of making and shipping all units, which it shaped to stack like paper cups for easy transportation and storage.

In the 1990s, manufacturers and installers of fiberglass and package pools set a new goal for the ’90s — to make their pools look as customized as gunite. Vinyl installers now enjoy many more liner patterns, some with three-dimensional tile looks, as well as fiberoptic applications; the ability to cantilever decks over wall assemblies and to install waterfeatures. A few pioneers have even installed vinyl-liner vanishing edges on package pools.

After the development of CAD, fiberglass manufacturers, in turn, began molding one-piece units into more and more shapes. They also made materials more durable in the mid-’80s at the prompting of the boating industry. Having already begun using ceramic waterline tile and developed a system to cantilever decks in the late-’70s, they also have found ways to incorporate these and other modern extras such as raised-beam waterfalls and spillover spas.