The gap comes down to asset class dominance and leverage. Harriman didn't just own oil wells or refineries—he controlled the physical arteries of American commerce: over 120,000 miles of railroad track that every business needed to use. This created a perpetual toll booth on the entire economy. Rockefeller, despite controlling 90% of oil refining, was still selling a commodity product competing globally; Harriman was literally the only path goods could travel. In 1909 dollars, Harriman's $70M was borderline incomprehensible leverage over the economy.

Rockefeller's wealth was also fragmented by antitrust action in 1911—just two years after Harriman's death. The breakup of Standard Oil scattered his assets into 34 separate companies, diluting his control premium. While he theoretically became wealthier on paper through the distributed shares, his operational power and consolidated net worth metrics cratered compared to what Harriman maintained until his deathbed. Harriman faced no such regulatory dismantling; the railroad monopoly was already grandfathered in as "essential infrastructure" that governments protected rather than prosecuted.

The real kicker is that Harriman's $11.2B represents real infrastructure equity—tangible assets generating perpetual cash flows through capital requirements. Rockefeller's $340M (the adjusted figure in this comparison) reflects peak market valuation at the moment before fragmentation. Had Standard Oil never been broken up, Rockefeller's consolidated empire might've rivaled Harriman's, but the judiciary's hammer fell harder on oil monopolies than on railroad barons who'd already baked themselves into the system's foundation.