Unable to agree on any particular method for selecting presidential electors, the Founders left the choice of method exclusively to the states in Article II, Section 1
“Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors….”  
The U.S. Supreme Court has repeatedly characterized the authority of the state legislatures over the manner of awarding their electoral votes as "plenary" and "exclusive."

In 1789, in the nation's first election, a majority of the states appointed their presidential electors by appointment by the legislature or by the governor and his cabinet, the people had no vote for President in most states, and in them, only men who owned a substantial amount of property could vote, and only three states used the state-by-state winner-take-all method to award electoral votes.

The constitutional wording does not encourage, discourage, require, or prohibit the use of any particular method for awarding a state's electoral votes.