Peace Science Digest

Why Do U.S. Congress Members Vote for Military Spending?

This analysis summarizes and reflects on the following research: Seiglie, C. & Xiang, J. (2021). Explanations of military spending: The evidence from legislators. Defence and Peace Economics, Online.

Talking Points

In the context of the 112th U.S. House of Representatives:

  • Legislators’ party affiliation and the demographics of their districts account for differences in the legislative vote on military spending.
  • Democrats were more likely than their Republican colleagues to oppose military spending.
  • Districts with a higher percentage of veterans and a lower rate of unemployment were more likely to support military spending, whereas districts with higher education rates were more likely to support military spending cuts.

Key Insight for Informing Practice

  • Focusing on domestic politics and its influence on military spending reveals pathways for countering seemingly limitless increases in the defense budget—whether by questioning the necessity of current levels of spending to addressing external security threats or by highlighting the negative effects of military spending.


There are numerous explanations for military spending­­­­, including the influence of international arms races, budgetary trade-offs and economic effects, public opinion on the military, and the military industrial complex. Carlos Seiglie and Jun Xiang present a novel explanation for military spending that focuses on legislators’ preferences. By examining roll call data from the 112th U.S. House of Representatives (2011-2013), they find that legislators’ party affiliation and the demographics of their districts account for differences in the legislative vote on military spending.  

The authors ran a series of statistical tests to see which factors were most closely associated with legislators’ preferences on military spending. Variables included legislators’ personal attributes (such as their party affiliation, gender, and former military service); the military industrial complex (measured by the existence of a military installation or arms manufacturer in their district and contributions from defense industry interest groups); district demographics (the percentage of veterans and college educated voters, as well as the unemployment rate); and public opinion (measured by survey results that calculated “the percentage of district voters that favor a military spending cut to reduce the deficit”).  

Initial tests showed that party affiliation correlated most closely with differences in legislators’ votes on military spending. Democrats were more opposed to military spending than their Republican colleagues. This is not a surprising finding if one looks at the vote for the National Defense Authorization Act during the 112th Congress: The overall vote was 299 in favor, 120 opposed, with 104 Democrats and only 15 Republicans among those opposed.

Further, the demographics of a legislator’s district exerted a strong influence on their voting record. Districts with a higher percentage of veterans and a lower rate of unemployment were more likely to support military spending. Districts with higher education rates, however, were more likely to support military spending cuts. Interest group contributions also increased the likelihood that a legislator would support military spending but did not appear as influential as party affiliation or district demographics. Interestingly, the presence of military installations or arms manufacturers in a district and public opinion did not appear to be influential. These findings were then confirmed after additional testing. 

Informing Practice

By focusing on the influence of domestic politics on military spending, this research reveals new pathways for countering seemingly limitless increases in the defense budget.

First, given the link made by many (but especially Republican) legislators between military spending and national security, a key pathway to limiting military spending is to question this link. While legislators may support increases in military spending to signal strength or security to voters—the sense that something can be done in the face of external military threats—it is not clear that more military spending will actually help mitigate these threats. For instance, in the wake of Russia’s invasion of Ukraine, calls to increase military spending may appeal to U.S. voters and help legislators gain political support—even though the U.S. has (wisely) stated that no U.S. troops will be sent to Ukraine. With already high rates of military spending in the U.S. and a strategy to avoid a military campaign in Ukraine, it is unclear what the added value of additional military spending would be to addressing the crisis, especially with evidence that half goes to private defense contractors anyway. In this case, increasing military spending may appeal to voters simply because it gives the impression of doing something, while benefiting the interest of defense contractors—all of which is driven by domestic political considerations (in an election year no less). Furthermore, even more critically, high military spending—and the militarization of conflicts and relationships that it creates—can exacerbate the very security threats it is meant to mitigate, while also actively undermining opportunities for collaboration or diplomacy (in areas like climate change or nuclear weapons). In short, we must amplify the too-few voices in Congress questioning the necessity of massive amounts of military spending to national security—as well as highlight the fact that the Pentagon has repeatedly failed audits since 2017.

Second, a focus on military spending through the lens of domestic politics also forces us to contend with—and enables us to better highlight—the negative domestic and global effects of military spending. There is evidence of a trade-off between military spending and healthcare wherein a 1% increase in military spending contributes to a 0.962% drop in spending on healthcare. With the world still reeling from the COVID-19 pandemic, there is a substantial need for spending on healthcare to address worker shortages, vaccine development, and long-term treatment. Additionally, increased military spending can lead to slower economic growth, a bad strategy to rebuild economies severely disrupted by COVID-19. Finally, giving more money to the military without meaningfully reining in their carbon emissions further fuels the climate crisis.

Increasing military spending without clarity on the nature of genuine security threats and how military spending will actually address these, without budgetary accountability to avoid corruption and waste of public funds, and without recognition of the negative effects of such spending actually makes us less secure. It hampers our ability to solve problems—especially problems that pose an existential threat (like pandemics or climate change). [KC]

Questions Raised

  • How can concerned parties best highlight the ways increased military spending actually make individuals and communities less secure?

Continued Reading and Listening

Things That Go Boom. (2021, August 30). Take this job and shove it. Accessed March 1, 2022, from

Peace Science Digest. (2019, June 6). When countries increase their military budgets, they decrease public health spending. Accessed March 1, 2022, from   

Peace Science Digest. (2019, December 9). Threats, public support, and military intervention. Accessed March 1, 2022, from

Peace Science Digest. (2018, January 2). The effects of military spending on economic growth. Accessed March 1, 2022, from

Chappell, B. (2021, May 19). The Pentagon has never passed an audit. Some senators want to change that. NPR. Accessed March 2, 2022, from

Crawford, N. (2019, November 13). Pentagon fuel use, climate change, and the costs of war. The Costs of War Project. Accessed March 2, 2022, from


Poor People’s Campaign:  

The Costs of War Project:

Quincy Institute for Responsible Statecraft:

Institute for Policy Studies:

Keywords: military spending, voting, U.S. House of Representatives

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