PRINCETON, N.J. — THIS has been a tough season for commuters in the New York region: the Amtrak crash in May, trains stuck in Hudson River tunnels in June, subway service disrupted by never-ending summer construction. Still, more than 5.6 million people take the subway each weekday, the most since 1949; New Jersey Transit’s ridership into the city has risen 75 percent in the past 15 years, and Amtrak’s Northeast Corridor carried a record of nearly 12 million riders last year.

Why are our transit systems faltering just as more people than ever want to use them? Part of the answer lies with the way our government institutions are structured, and New York offers a case in point.

Private companies built many of our subways, commuter lines and intercity railroads in the late 19th and early 20th centuries. Mass transit, like long-distance rail, was profitable then, especially when combined with speculation in land made accessible by new, fast rail connections.

Then came the automobile, and publicly funded highways. Public authorities like the Port of New York Authority (formed in 1921) and the Triborough Bridge and Tunnel Authority (1933) took charge of building highways, bridges and tunnels for this liberating technology.