William_T._Bianco,_David_T._Canon]_American_Polit

400 Chapter 11 | Congress

levels in the post–World War II era in recent years. About 70 percent of all roll call votes

were party votes, in which a majority of one party opposed a majority of the other

party. The proportion of party votes fell to between 50 and 60 percent between 1996

and 2008 but recently has hit new highs. The highest proportions were 72 percent in

the Senate in 2009 and 75.8 percent in the House in 2011; the numbers remained at

about those levels in the House, but fell in the Senate in 2016. In the last year of Obama’s

tenure, not much happened in the Senate (former Republican leader Trent Lott called

the Senate’s output a “nothing burger”). Partisanship returned in 2017 with the Tax

Cuts and Jobs Act, which passed with razor-thin margins. Party unity, the percentage

of party members voting together on party votes, soared during this period as well,

especially in the House. Party unity hit an all-time high for House Republicans in 2016,

with 93 percent of them voting together on party vote. House Democrats were almost as

unified at 91 percent.^29

Party-line votes have become more common as the Democratic Party has become

more cohesive: southern Democrats now vote more like their northern counterparts,

partly because of the importance of African-American voters, who tend to vote for

Democrats in the South. Moreover, increasing Republican strength in the South

means that the remaining Democratic districts are more liberal, because Republicans

defeat the more moderate Democrats. Similarly, there are fewer moderates within

the Republican Party, as most regions of the country that used to elect moderate

Republicans are now electing Democrats.^30

Another way to examine changes in the composition of the parties is to examine

the ideological distribution of members of Congress (see Figure 11.6). The parties in

Congress are now more polarized than they have been at any point in U.S. history. In

the 1970s, there was considerable overlap between the Democratic and Republican

roll call vote

A recorded vote on legislation;

members may vote yes, no, abstain,

or present.

party vote

A vote in which the majority of one

party opposes the position of the

majority of the other party.

party unity

The extent to which members of

Congress in the same party vote

together on party votes.

FIGURE

11.6

Source: Polarization in Congress, “Liberal-Conservative Partisan Polarization by Chamber,” Jeff Lewis, March 11, 2018, https://voteview.com/

articles/party_polarization (accessed 6/7/18).

1880 1888 1896 1904 1912 1920 1928 1936 1944 1952 1960 1968 1976 1984 1992 2000 2008 2016

0.8

Ideological distance between the parties in each chamber

0.7

0.9

0.6

0.5

0.4

Senate

House

Ideological Polarization in Congress, 1879–2017

Although party polarization in Congress has been high in the past, it lessened in the early twentieth century. Polarization has increased

steadily in the last 70 years, and today’s Congress is more polarized than ever. What do you think causes this extreme polarization?

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