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Landmark day • Thursday, September 20, 1906

September 20, 1906: The First Stone of Roosevelt Dam

Eighty miles upstream, in a canyon the Valley's farmers had mortgaged their land to build in, the first six-ton block goes down — the day the dam stopped being a promise.

Illustrated plaque for September 20, 1906 in Scottsdale history SEPTEMBER 20 1906 FOUNDING & PIONEER YEARS

What happened

Stonemasons — many of them Italian immigrants recruited from Pennsylvania quarries — eased a six-ton cornerstone into place at the base of the Roosevelt Dam site, thirty-two feet below the river's normal bed at the mouth of Tonto Creek. It was the first of the cut-stone blocks that would rise 280 feet over the next four and a half years into the tallest masonry dam in the world. The last stone was laid February 6, 1911.

Why it matters

From the cornerstone forward the drought-proof water Scottsdale had bet on in 1903 was a structure rising in the canyon rather than a line in a contract. Reliable irrigation from the finished dam underwrote the cotton boom, the winter-resort trade, and everything the town became.

Three years of getting ready

The contract of June 1904 had committed the government to a dam; the site had committed the government to a great deal of preparatory work first. The mouth of Tonto Creek was sixty miles of mountain from the nearest railhead, so the Reclamation Service built its own road up through the Superstitions — the Apache Trail, graded largely by Apache crews — then a cement mill, a sawmill, a power canal to generate electricity for the site, and a town for the workers. Floods on the Salt twice washed out the cofferdams and set the schedule back. Only in the late summer of 1906, with the foundation excavated to bedrock thirty-two feet below the riverbed, was the site ready for stone.

On September 20, 1906, the first block went down: a six-ton cut stone lowered into the excavation by a crew of masons. Most of them were Italian immigrants, brought west from the quarries of Pennsylvania because the Service wanted the dam built the old way — dressed rubble masonry laid in cement, a technique that would give Roosevelt Dam its cyclopean look and, at 280 feet, make it the tallest masonry dam on earth. The Valley’s newspapers covered it as the beginning of the end of the drought years. They were right, though the end was still four and a half years away.

What the Valley saw from below

Down on the benchland the dam was invisible and its effect was immediate. The families who had pledged their farms in 1903 had spent three years on faith; now there was masonry to point to, and every course of stone that went up was a reason to stay. The Reclamation Service had also taken over the Valley’s canals under the 1904 contract, and its engineers were already building Granite Reef Diversion Dam downstream — begun the following month, finished in 1908 — to replace the wooden works the 1905 flood had destroyed and feed the Arizona Canal that ran past Scottsdale.

The last stone was laid February 6, 1911, and Theodore Roosevelt came in person to dedicate the dam on March 18, 1911. Winfield Scott, who had preached and boosted through the whole drought, died in October 1910 without seeing it finished. The rest of the year is at 1906, and the decade of drought and rescue in the 1900s chapter.