Champion v. Ames (1903) 188 U.S. 321

"As a state may, for the purpose of guarding the morals of its own people, forbid all sales of lottery tickets within its limits, so Congress, for the purpose of guarding the people of the United States against the "widespread pestilence of lotteries" and to protect the commerce which concerns all the states, may prohibit the carrying of lottery tickets from one state to another."