Final answer:
House party unity voting is higher due to the House's structured leadership and ability to control the legislative process, while the Senate's longer terms and traditions of extended debate encourage more bipartisan efforts and individual senator autonomy.
Step-by-step explanation:
Party unity voting in the House is typically higher than in the Senate primarily because of the structured leadership and the majoritarian characteristics of the House. The House party leadership has more control over access to the floor, which can pressure members into party unity voting. Additionally, the party leadership in the House can use special rules to guide bills through the legislative process with restrictive debate and limited options, shaping the direction of the vote. In contrast, the Senate values extended debate and individual senator's autonomy, making it more conducive to bipartisan decision-making. Senators have longer terms, represent entire states, and are less subject to the immediate pressures of constituents, thus they may exhibit greater independence from their party's line and have a higher likelihood of crossing party lines to work with colleagues on legislation.