Edward Douglass White, Howard v. Illinois Central Railroad Company…
“ In every form of transportation, from the simplest to the most complex, whether the man carries the burden on his back, or drives an animal which carries it, or a locomotive which draws a car which carries it, the one and only constant factor is the labor of mankind. I am quite unable to understand the contention made at the bar that the power of Congress is to regulate commerce among the states, and not to regulate persons engaged in commerce among the states, for, in the case of transportation, at least, the labor of those engaged in it is commerce itself. ”
