Rock Products - The Leading Voice of the Aggregate Industries.

Rock Products 120th Anniversary - Part 4


In This Issue, We Cover The Years 1930-1939.

26 120YEARS 400The Wall Street crash in October 1929 sent the country spiraling downward into what became known as the Great Depression. Between 1929 and 1932, approximately 11,000 United States banks failed, and about $2 billion in bank deposits were lost. Industrial stocks lost 80 percent of their value between 1930 and 1933.

Between 1929 and 1932, the Gross National Product (GNP) declined at a rate of about 10 percent per year, whereas in the previous decade it had risen at a rate of about 3.5 percent annually. In 1930, 4.5 million people in the United States were unemployed; by 1932, unemployment had reached 5.6 million.

The industries hit hardest by the depression were connected to coal, railroads, mining and textiles. The rock products industry watched as almost nine contiguous years of prosperity seemingly went down the drain. Aggregate production in 1929 had reached 361 million tons; in 1933, it was only 176 million tons. Crushed stone production dropped from 141 million tons in 1929 to 70 million tons in 1933; sand and gravel from 220 million tons in 1929 to 106 million tons in 1933.

28 120th 400The cement industry witnessed the same slump in production. In 1929, production of portland cement in the United States was at a record 32 million tons, but by 1933, production was only 11.9 million tons. It was estimated in 1932 that, by the end of that year, the cement industry would lose about $25 million in production in two years’ time. In 1932, the cement industry was functioning at only 50 percent capacity.


Business philosophy in the early 1930s focused on confidence, and the editor of Rock Products cautioned readers that, “unless a general renewal of confidence takes place, unless those with confidence take decisive and prompt action, we may have to wait until most of our clothes, furniture, residences automobiles, etc., are worn out beyond all possible use before business can return to normal.”

One operation that exhibited this confidence was the New York Trap Rock Corp. in Stoneco, N.Y., in operation since 1888, which increased capacity in 1930 with the construction of a new plant.

Highway construction, though cut back considerably, remained a huge employer throughout the depression. Frederick F. Everett, president of the American Association of State Highway Officials, said in 1932 that, “even during the quiet of 1931 … highway and street building employed 1 million workers directly, and the labor of 2 million others was required in supplying equipment and materials. But if during the last few years, highway construction had lagged, no one knows how much more serious economic conditions would be at present.”

But highway construction was threatened in 1932, when legislators proposed to divert gasoline taxes that paid for construction to instead pay for public service programs. Rock Products offered that, “such diversions break faith with the motorist. The popularity of the gasoline tax is entirely dependent upon the use of the proceeds to provide good roads.”




Crushed Stone

Sand & Gravel














































Source: US Geological Survey   million short tons

Rock Products reported in 1932 that, “many sections of the country are building so-called ‘low-cost road,’ which utilizes unwashed gravel, run-of-bank slag, red-dog, cinders, and the output from stone quarries not suitable for concrete pavements.” Development of these cheaper road materials placed a severe handicap on producers of high-grade aggregates, who were unable to offer competitive prices.

The discovery of Colorado vermiculite led producers to consider making more economical and efficient high-temperature insulation methods. The “new industry of air conditioning” swept across the country, and production of rock wool, slag wool, gypsum and concrete products, vermiculite, pumice, volcanic ash, diatomaceous earth and other materials rose in an attempt by producers to develop the best insulation.

The rock products industry in the 1930s was becoming more and more regulated by the government. Rock Products reported in 1932 that, “more stringent state laws in regard to size of quarry blasts and new laws pertaining to the handling of high explosives … are likely to become live subjects in all of the more thickly populated states where quarries are near centers of population or industry.”

Plant Design

The design of aggregate plants had changed significantly through the last decade; Rock Products in 1932 reported that, “an old timer returning to this country after an absence of 10 or 12 years would not recognize a crushed-stone plant.”

In 1932, alloys began to play a part in reducing repair costs at crushing plants and other industry operations. Alloys were also incorporated into buckets for bucket conveyors, extending their life and service.

Portable plants came into wider use in the early 1930s. Producers in the early part of the decade considered making their own electric power. Emphasis in equipment development was often placed on power savings. Vibrating screens were preferred over revolving screens, conveyors were equipped with anti-friction bearings, and pressure lubricating enclosed gear drives were used.

  • “Automatic control,” a precursor to today’s automation technologies, was becoming a topic of great interest to the industry in 1931. Instruments for indicating and recording measurements also gained wider use in the early part of the decade.
  • One of the most important developments of the decade in quarry transportation equipment was the use of remote-controlled, alternating-current electric haulage systems.
  • Tractors were replacing trucks for earth moving in highway construction. With the development of various types of equipment, including power scoops, air compressors, cranes, and hoists, for tractor mounting, the tractor took on increased importance in rock products operations.
  • A track-type tractor with 12-in.-wide track shoes was introduced by Allis-Chalmers in Milwaukee, Wis., during the early part of the decade.
  • A conveyor belt with magnetic “feelers” to pick up tramp iron from a belt below was introduced in 1930.
  • Dings Magnetic Separator Co. introduced a “high-intensity” separator in 1932, which it claimed could separate slate from gypsum, among other things.
  • Manufacturers in the early 1930s began to make motor truck bodies available with some of the same features of quarry cars, as some large quarries were replacing rail and cars 15-ton trucks with 10-cu.-yd. bodies, which dumped to skip hoists that elevated material to the crusher house.
  • Three-way power dumping also was developed, and special gravel spreaders were created for use in conjunction with dump trucks for even spreading of road materials.

In the cement industry, pneumatic conveying gained popularity. The Fuller-Kinyon Conveying System had been developed during the late 1920s, and by 1932, pneumatic conveying equipment was installed in many cement and ready-mixed concrete operations.

In the early part of the decade, the cement industry made efforts to introduce wet-closed circuit grinding with ballmills, classifiers and thickeners. In Europe, manufacturers began to experiment with a method of burning cement by combining a travelling grate with a rotary kiln. The rotary kiln also was at the center of U.S. cement industry research in 1931.

Ready Mix

The use of ready-mixed concrete grew in the first half of the decade. In 1931, the National Ready Mixed Concrete Association held its first annual convention in St. Louis.

30 120th 400The committee on central-and truck-mixed concrete of the American Road Builders Association in the same year reported favorably on the use of ready-mixed concrete in construction of streets and highways.

Franklin D. Roosevelt was elected on his New Deal platform in 1932, and began in 1933 to institute programs to bolster the nation’s employment levels and economy. The National Recovery Administration (NRA) was part of the program, and, under its terms, the National Industrial Recovery Act (NIRA) was created.

The NRA set rules that allowed businesses to draft (subject to presidential approval) “codes of fair competition” that regulated prices, working conditions, wages, plant construction, and credit terms. Antitrust laws would not apply to businesses who complied with the codes. The NRA also granted workers the right to form unions.

The Public Works Administration (PWA) was created under the NIRA, and was designed to stimulate development by putting federal funds into large-scale construction projects.
The NRA, NIRA and PWA all seemed to hold promise for producers in the rock products industry. While many anticipated that the New Deal would lead them out of economic despair and into prosperity that remained to be seen.

The New Deal: 1934-1936

The induction of the New Deal brought with it a rush of confidence in the country. Production in 1934 was again on the rise: in one year, aggregate production climbed 15 percent, from 176 million tons in 1933 to 206 million tons in 1934. Production of portland cement rose as well, from about 12 million tons in 1933 to 14.6 million tons in the following year. Growth would continue steadily until 1938, when it would drop off briefly for a year and then rise again on its way back to record levels.

But many of the programs associated with the New Deal did not please the rock products industry.

The Works Progress Administration (WPA), authorized by Congress in 1935, was seen as the biggest threat resulting from the New Deal assistance programs. The program was supposed to provide useful work during a period of massive unemployment, but many producers viewed it as a competitor, not as help. Producers doubted that any long-term benefits would result from the enactment of the program.

Many towns, counties and road districts were given money to invest in small plants for the production of crushed stone and other construction products, but it was widely known among those in the industry that these workers, who often slowed production and produced inferior materials.

In 1935, the Boards of Directors of the National Crushed Stone Association, the National Sand and Gravel Association, and the National Slag Association (NSA) resolved in the pages of Rock Products to condemn the passage of the WPA. In particular, members of the rock products industry argued that the WPA’s rules held “the active threat of increasing the governmental production of crushed stone, and sand and gravel, not already at a point which endangers the continuance of private enterprise in these important fields.”

By 1937, the WPA had spent more than $31 million to employ workers in the cement industry. The agency spent $17 million worth of funds to pay concrete products workers, almost $23 million for workers in the sand and gravel industry, and about $18.3 million to employ people working with crushed stone.

A higher number of accidents in rock products operations in the late 1930s was often attributed to the large number of unskilled employees occupying the plants. Monthly death bulletins began to appear in Rock Products, accompanied by safety reports and helpful reminders.

The National Labor Relations Act (NLRA) was passed by Congress in 1935, and was intended to encourage and regulate collective bargaining. The Committee for Industrial Organization was formed that same year.

Although the Wagner Act, as the NLRA was more commonly called, was declared unconstitutional in 1937, in the two-and-a-half years it was legally applied it stimulated union growth and power.

In 1938, a national minimum wage was established of 25 cents-per-hour, with work weeks not longer than 44 hours; child labor was officially prohibited.

The one program formed under the NRA that the rock products industry did favor was the Public Works Administration (PWA), which spent $6 billion between 1933 and 1939 on large-scale construction projects. The PWA funded both its own projects and those started by federal agencies and state governments.

Large Projects

Several large construction projects in the United States kept thousands of workers employed throughout the worst years of the depression. Boulder Dam, the construction of which employed thousands of workers, was finished in Arizona in 1936 (and later renamed Hoover Dam in 1947). That same year, construction on the Grant Coulee Dam began. The project was projected to consume 11 million cu. yd. of aggregate.

Road construction also continued to bring guaranteed employment to thousands of people throughout the late 1930s. About $1.8 billion in federal and state funds were earmarked for road construction during 1936.

It was found in 1936 that diversion of road funds, which the rock products industry had fought during the early 1930s, resulted in $545 million in taxes lost to other services between 1926 and 1936.

One of the most pressing issues for those in the rock products industry was the growing incidence of silicosis. It was defined in 1937 as “strictly an industrial disease of the lung due to breathing air containing silica dust or quartz dust.” Dr. R.R. Sayers, medical officer in charge of industrial hygiene, U.S. Public Health Service, said that he believed there was enough technology in the industry to prevent instances of silicosis.

A great amount of attention in the industry was focused on people believed to be scam artists in a “silicosis racket.” An article in Rock Products in 1937 detailed a case in St. Louis County where a lawyer was found guilty of paying medical expenses and court costs for a number of silicosis patients in order to glean profit from their silicosis settlements against producers.

Equipment developments during the late 1930s were minor, as producers focused more on power, cost savings and upkeep than on anything else.

  • A combined blower and dust precipitator for dust control was introduced in 1934. In 1936, Spokane Portland Cement Co. in Irvin, Wash., installed a Lepol kiln, the first of its type on the continent.
  • In 1935, the longest conveyor in existence measured 904 ft. long; three years later the record for conveyor length was 9,700 ft.
  • B.F. Goodrich Co. developed rubber tracks in 1938, which would make possible the handling of bigger loads.
  • In 1937, the Robins Conveying Belt Co. introduced a low-head horizontal screen, operating with elliptical stroke. The Pioneer Gravel Equipment Manufacturing Co. introduced its horizontal balance screen during the same year.
  • Atlas Powder Co. offered the first triple-fifty blasting machine in 1937, designed to shoot 150 holes simultaneously.
  • The rapid increase in use of diesel trucks over the previous years resulted in lower transportation expenditures during the late 1930s.

By 1937, a sense of optimism in the United States was growing. Rock Products featured a company that was building giant concrete dinosaurs for a “Dinosaur Park” in Rapid City, S.D. And by 1938, the country was rapidly re-building itself economically, and industry experts predicted a housing boom in the coming years. Within the next two years, the rock products industry would again be producing at pre-1930s levels and enjoying prosperity. 

Next Month: The World at War: The 1940s.