The separate opinion of Mr. Justice McREYNOLDS.
I am of opinion that the courts below reached correct conclusions in these causes.
The states have spent enormous sums in constructing roads, and must continue to maintain and protect them at great cost if they are to remain fit for travel.
The problems arising out of the sudden increase of motor vehicles present extraordinary difficulties. As yet nobody definitely knows what should be done. Manifestly, the exigency cannot be met through uniform rules laid down by Congress.
Interstate commerce has been greatly aided-amazingly facilitated, indeed-through legislation and expenditures by the states. The challenged statutes do not discriminate against such commerce, do not seriously impede it, and indicate an honest purpose to promote the best interest of all by preventing unnecessary destruction and keeping the ways fit for maximum service.
The federal government has not and cannot undertake precise regulation. Control by the states must continue; otherwise chaotic conditions will quickly develop. The problems are essentially local, and should be left with the local authorities unless and until something is done which really tends to obstruct the free flow of commercial in tercourse.
The situation is similar to the one growing out of the necessity for harbor regulations. State statutes concerning pilotage, for example, have been upheld although they [267 U.S. 325, 326] amounted to regulation of interstate and foreign commerce. 'They fall within that class of powers which may be exercised by the state until Congress has seen fit to act upon the subject.' Olsen v. Smith, 195 U.S. 332, 341 , 25 S. Ct. 52, 53 (49 L. Ed. 224).