_Pure Food._--Congress has also provided for the inspection of foods imported from abroad. Whenever a vessel is found to have on board impure or adulterated foods or teas, it is forbidden to land the cargo or is allowed to land it only after certain conditions are complied with such as the change of labels to correspond with the actual contents of packages. In this way an attempt is made to protect the American consumer against impure and unwholesome food products shipped here from foreign ports. =Interstate Commerce= has been interpreted to include the carriage of passengers from one state to another; the transportation of commodities of whatsoever character, including lottery tickets, obscene literature, and any other objects which may be the subject of transportation; and the transmission of ideas or information by telegraph or telephone from a point in one state to a point in another. In short, interstate commerce means not only transportation and traffic in articles but intercourse and communication by the modern devices for transmitting thought; and the power to prescribe the conditions under which such intercourse may be carried on across state lines belongs to Congress.[43] Congress controls also the coasting trade between parts of the same state and the traffic on all rivers which flow into the ocean or the Great Lakes and thus constitute highways of interstate or foreign commerce. [43] Under the commerce power. Congress has also enacted the white slave law, and an act restricting the killing of birds that migrate from one state to another. [Illustration: IMMIGRATION STATION, ELLIS ISLAND, NEW YORK HARBOR] [Illustration: IMMIGRANTS READY TO START WEST] _Power Retained by the States._--Nevertheless it is often difficult in a particular case to draw the line between acts which regulate interstate commerce and acts which merely affect it without regulating it. The Supreme Court in a long line of decisions has held that the states not only have complete power of control over all commerce originating and ending within their limits but that they may also enact legislation for the protection of the public health, safety, good order, and morals of their people even when such legislation affects commerce among the states, the only restriction being that such legislation must be reasonable and must not amount to a direct interference with interstate traffic. The right of the states in this respect is known as the _police power_--a power which is very extensive and of which they cannot be deprived by Congress. Thus they may enact reasonable quarantine laws forbidding the entrance into their territory of diseased persons from other states or the importation of diseased live stock. Likewise they may limit the speed of interstate trains running through their towns, may require railroads to provide gates at crossings, safety appliances for cars, and the like.