2 CHIAFALO v. WASHINGTON Syllabus such Manner as the Legislature thereof may direct.” This Court has described that clause as “conveying the broadest power of determination” over who becomes an elector. McPherson v. Blacker, 146 U. S. 1, 27. And the power to appoint an elector (in any manner) includes power to condition his appointment, absent some other constitutional constraint. A State can require, for example, that an elector live in the State or qualify as a regular voter during the relevant time period. Or more substantively, a State can insist (as Ray allowed) that the elector pledge to cast his Electoral College ballot for his party’s presidential nominee, thus tracking the State’s popular vote. Or—so long as nothing else in the Constitution poses an obstacle—a State can add an associated condition of appointment: It can demand that the elector actually live up to his pledge, on pain of penalty. Which is to say that the State’s appointment power, barring some outside constraint, enables the enforcement of a pledge like Washington’s. Nothing in the Constitution expressly prohibits States from taking away presidential electors’ voting discretion as Washington does. Article II includes only the instruction to each State to appoint electors, and the Twelfth Amendment only sets out the electors’ voting procedures. And while two contemporaneous State Constitutions incorporated language calling for the exercise of elector discretion, no language of that kind made it into the Federal Constitution. Contrary to the Electors’ argument, Article II’s use of the term “electors” and the Twelfth Amendment’s requirement that the electors “vote,” and that they do so “by ballot,” do not establish that electors must have discretion. The Electors and their amici object that the Framers using those words expected the Electors’ votes to reflect their own judgments. But even assuming that outlook was widely shared, it would not be enough. Whether by choice or accident, the Framers did not reduce their thoughts about electors’ discretion to the printed page. Pp. 8–13. (b) “Long settled and established practice” may have “great weight in a proper interpretation of constitutional provisions.” The Pocket Veto Case, 279 U. S. 655, 689. The Electors make an appeal to that kind of practice in asserting their right to independence, but “our whole experience as a Nation” points in the opposite direction. NLRB v. Noel Canning, 573 U. S. 513, 557. From the first elections under the Constitution, States sent electors to the College to vote for pre-selected candidates, rather than to use their own judgment. The electors rapidly settled into that non-discretionary role. See Ray, 343 U. S., at 228–229. Ratified at the start of the 19th century, the Twelfth Amendment both acknowledged and facilitated the Electoral College’s emergence as a mechanism not for deliberation but for party-line voting. Courts and commentators throughout that century recognized the presidential electors as merely acting on other people’s preferences.