Final answer:
Legislators vote for spending projects in other districts due to pork-barrel spending and logrolling, where they trade support to mutually benefit their districts and enhance their political standing.
Step-by-step explanation:
The question is asking why legislators might vote for spending projects in districts other than their own. Legislators often engage in pork-barrel spending, which includes projects that are intended to benefit a particular district and have the support of the local legislator. This is a strategic move where costs are dispersed across the country, but the benefits are concentrated in a specific area, often leading to a quid pro quo situation.
This practice can enhance their political standing and can be a form of logrolling, where legislators trade favors to gain support for their own projects or legislation. Additionally, the spread of spending on military bases and weapons programs across various districts encourages members of Congress to vote in support of defense spending, ensuring that each receives benefits for their own constituencies.