A fost scholars agree that members of Congress are strongly motivated by their desire for reelection. This assumption implies that members of Congress adopt institutions, rules, and norms of behavior in part 1LYE. to serve their electoral interests. Direct tests of the electoral connection are rare, however, because significant, exogenous changes in the electoral environment are difficult to identify. We develop and test an electoral rationale for the norm of committee assignment "property rights." We examine committee tenure patterns before and after a major, exogenous change in the electoral system-the states' rapid adoption of Australian ballot laws in the early 1890s. The ballot changes, we argue, induced new "personal vote" electoral incentives, which contributed to the adoption of "modem" congressional institutions such as property rights to committee assignments. We demonstrate a marked increase in assignment stability after 1892, by which time a majority of states had put the new ballot laws into force, and earlier than previous studies have suggested.A common theme in research on congressional institutions is that members of Congress adopt institutions and rules that serve their desire for reelection. Important structural features of the committee system, for example, should be explicable in terms of their effects on reelection efforts. Often criticized, this Mayhewian reelection incentive premise is itself almost never put to the test, for the simple reason that significant changes in American electoral institutions have been quite rare.We shall develop and test an explicit, electoral explanation for one of the key features of the modern House committee system-the norm of reappointing incumbent members of Congress to their same committee assignments at the start of each Congress. We argue that this so-called property right norm of reappointment reflects personalistic reelection incentives arising from the single-member district, secret ballot electoral system used in U.S. states.The states' conversion from party-strip balloting to Australian (secret) ballots in the 1890s profoundly altered the electoral environment faced by incumbent members of Congress. The secret ballot allows voters to reward or punish each of their elected representatives (local, state, and national, all of whom might appear on the same ballot) individually. These reforms, we argue, made credit-claiming and other personal vote activities by members of Congress significantly more important for reelection, even at the very height of "strong party government" in the United States (Brady 1973).The changes in balloting, therefore, were a key pre- cursor to House adoption of a host of "modern" practices with important credit-claiming effects, from the reappointment norm to the expansion of professional staffs. Secure committee tenure allowed incumbent members of Congress to develop "careerist" patterns of behavior in the House (Price 1977)-including committee-related policy expertise-that provided fuel for increased legislative activity ...