… is from page 120 of my good friend and former professor Randy Holcombe’s superb 2019 book, Liberty in Peril: Democracy and Power in American History:
The railroads [in the decades immediately following the U.S. civil war] saw advantages to regulation. Unstable prices, disliked by rail customers, could also be detrimental to the railroads. A recession in 1884 led to the failure of a number of railroads, and the railroads wanted to undertake pooling arrangements for their mutual profitability. Thus, the railroad industry, which was very competitive, wanted the ICC [Interstate Commerce Commission] to stabilize rates, regulate routes, and protect their profitability. Essentially, the ICC cartelized the industry, allowing it to be more profitable than it could have been in a more competitive unregulated environment.