Does low voter turnout favor the Republican Party? Historically is there a causal relationship between turnout and political affiliation?
Establishing a causal relationship is hard.
There are established correlations between
- Income and turnout (in 2008 41% of those earning $10000 or less voted, compared with 78% of those earning $150000 or more)
- Ethnicity and turnout (in 2008 65% of "non-hispanic white" people voted, compared with 32% of "Hispanic" people.)
- Age and turnout
- Income and political preference (lower income people tend to vote Democrat)
- Ethnicity and political preference (White people tend to vote Republican)
- Age and political identification
It is therefore reasonable to suppose that there is a relationship between political identification and the likelihood of an individual voting, and non-voters are more likely to identify with the Democratic party. If there are more Democrats who are habitual non-voters, then efforts to encourage voting will tend to favour the Democratic party
What is less clear is whether the headline turnout rate affects the result. A low turnout can either be because Republicans or because Democrats stay at home.
Richard Nixon and Donald Trump won election with a turnout close to 60%, Clinton won in 1996 with one of the lowest turnouts, close to 52%. Considering Elections since 1960, There is little correlation: