Short answer: yes, it seems there is a correlation between socio-economical status and sweetened beverages consumption in the US.
There are a few very recent studies looking at drink consumption and different socio-economical descriptors. I will report some of them, although not all are related to the USA.
This first study looks at consumption patterns of sweetened beverages in the US
CONSUMPTION PATTERNS OF SUGAR SWEETENED BEVERAGES IN THE UNITED STATES - Han and Powell - J Acad Nutr Diet., 2013
A summary of the study (note SSBs = sugar sweetened beverages)
Trend and cross-sectional analyses of 24-hour dietary recall data and demographic characteristics and socioeconomic status (SES) drawn from the National Health and Nutrition Examination Survey (1999–2000, 2001–2002, 2003–2004, 2005–2006, and 2007–2008).
Children (2–11 years, N=8,627), adolescents (12–19 years, N=8,922), young adults (20–34 years, N=5,933), and middle-aged and elder adults (≥35 years, N=16,456).
Statistical analyses performed
Age-stratified regression analyses for SSBs overall and by subtypes.
And a summary of the results/conclusions (bold mine, SES=socio-economical status)
The prevalence of heavy total SSB consumption (≥500 kcal/day) increased among children (4% to 5%) although it decreased among adolescents (22% to 16%) and young adults (29% to 20%). Soda was the most heavily-consumed SSB in all age groups except for children. Prevalence of soda consumption decreased, whereas heavy sports/energy drink consumption tripled (4% to 12%) among adolescents. Black children and adolescents showed a higher odds of heavy fruit drink consumption (OR=1.71 and 1.67) than whites. Low-income children had a higher odds of heavy total SSB consumption (OR=1.93) and higher caloric intake from total SSBs and fruit drinks (by 23 and 27 kcal/day) than high-income children. Adolescents with low- versus high-educated parents had a higher odds of heavy total SSB consumption (OR=1.28) and higher caloric intake from total SSBs and soda (by 27 and 21 kcal/day). Low- versus high-SES was associated with a higher odds of heavy consumption of total SSBs, soda, and fruit drinks among adults.
Prevalence of soda consumption fell but non-traditional SSBs rose. Heterogeneity of heavy consumption by SSB types across racial/ethnic subpopulations and higher odds of heavy SSB consumption among low-SES populations should be considered in targeting policies to encourage healthful beverage consumption.
A detailed age/race/income breakdown of SSBs consumption is shown in Table 6 of the paper.
From the discussion (bold mine):
The previous literature reported greater odds of heavy consumption of regular soda among low-income adults and larger energy intake among children with low-educated parents. Results of the present study also indicated that low SES was a positive determinant of higher odds of heavy SSB consumption and higher caloric intake in all age groups including children. Children and adolescents in low SES showed a greater odds of heavy consumption of total SSBs (OR=1.93 and 1.28) and higher caloric intake from total SSBs (by 23 and 27 kcal/day), fruit drinks (by 27 kcal/day, children only), and regular soda (by 21 kcal/day, adolescents only). Such results may imply that low-income individuals may access SSBs more easily than other nutrient-dense beverages and/or water because of differences in availability or prices. Differential consumption among adolescents by parents’ education level also indicated the importance of the household environment in guiding youths’ more healthful beverage choices. Given that those populations in low SES reportedly had a higher prevalence of overweight and obesity, these results imply that those vulnerable populations should be included as important target populations for policy interventions. The study results also indicated that policies targeting the major form of SSBs, i.e., regular soda, can be effective for low-SES populations.
Another recent cross-sectional study looking at drink consumption in the US. Unfortunately they do not specifically look at soda vs ethnicity.
Water and beverage consumption among adults in the United States: cross-sectional study using data from NHANES 2005–2010 - Drewnowski et al. - BMC Public Health., 2013
The summary of the results (bold mine):
Water and other beverages contributed 75-84% of dietary water, with 17-25% provided by water in foods, depending on age. Plain water, from tap or bottled sources, contributed 30-37% of total dietary water. Overall, 56% of drinking water volume was from tap water while bottled water provided 44%. Older adults (≥71y) consumed much less bottled water than younger adults. Non-Hispanic whites consumed the most tap water, whereas Mexican-Americans consumed the most bottled water. Plain water consumption (bottled and tap) tended to be associated with higher incomes. On average, younger adults exceeded or came close to satisfying the DRIs for water. Older men and women failed to meet the Institute of Medicine (IOM) AI values, with a shortfall in daily water intakes of 1218 mL and 603 mL respectively. Eighty-three percent of women and 95% of men ≥71y failed to meet the IOM AI values for water. However, average water volume per 1,000 kcal was 1.2-1.4 L/1,000 kcal for most population sub-groups, higher than suggested levels of 1.0 L/1.000 kcal.
The study classified beverages into nine groups:
Water (bottled or tap), milk (including flavored), fruit juice (100%), soda/soft drinks (regular and diet), fruit drinks, sports/energy drinks, coffee, tea, and alcoholic beverages.
They first analyse plain water.
They found a decrease in total amount of consumed water with age, but no sex difference. However
There was a strong effect of socioeconomic status on consumption of water as a beverage. Adults with higher incomes consumed more water as a beverage than adults with lower incomes. There was no marked difference by race/ethnicity, though the other race/mixed race group consumed the most water as a beverage.
There were strong socio-demographic effects on type of water consumed. Non-Hispanic whites consumed the most tap water and the least bottled water (703 mL/d from tap vs. 437 mL/d from bottled). By contrast, Mexican Americans consumed the most bottled water (729 mL/d from bottled vs. 383 mL/d from tap). Lower-income adults consumed 603 mL/d of tap water as opposed to 721 mL/d for higher income adults. There was a strong effect of family income on consumption of tap water. For bottled water, compared to adults with higher family incomes, only those with the lowest family incomes consumed significantly less bottled water.
They then proceed to look at different beverages.
Figure 1 of the paper shows water intakes from beverage/food category by age and gender among US adults.
Finally, Table 4 gives a socio-economic brakeout of water consumption.
They show that
Adults 50-70y, women, non-Hispanic whites and adults with higher incomes consumed the most water dense diets.
It is, unfortunately, unclear what the breakout of that is.
However, the survey data is publicly available, so I will leave to the reader this interesting analysis.
A similar study from the same authors as the first one looks at drink consumption in South Korea, showing a different pattern than in the USA.
Beverage consumption and individual-level associations in South Korea - Han et al. - BMC Public Health, 2013
They report that (bold mine, note: SSBs = sugar-sweetened beverages)
Women (top- income group only) and men in higher income groups showed higher odds of consuming total SSBs (OR = 1.18-1.25), soda (OR = 1.18, men only), fruit drinks (OR = 1.18, the top-income only for both genders), and miscellaneous SSBs (OR = 1.1-1.2). Men with higher-education showed higher odds of total SSB consumption (OR = 1.14-1.20), and all subtypes of SSBs (OR = 1.18, 1.29, 1.19 for soda, fruit drinks, and miscellaneous SSBs, respectively for the top-education group only). There were statistically significant but minimal differences in the overall amount of caloric intake from SSBs by individual SES for both genders.
Note that they further break down the consumption and report that
Men in the near-top income group consumed more total SSBs (+2.3 kcal/day), fruit drinks (+1.6 kcal/day), and miscellaneous SSBs (+1.5 kcal/day). Education was positively associated with the amount of caloric intake only from regular soda (+2.0 kcal/day), although the magnitude of the association was minimal. Men with higher income and higher education also consumed more milk: the top-, near-top, and near-bottom income groups, respectively, consumed 7.3, 4.7, and 4.0 kcal/day more than the bottom-income quartile group; men with college or more and high school educations, respectively, consumed 5.5 and 15.5 kcal/day more than men with less than high school education
For reference, a similar study has been done on British people, although socio-economical status is not considered.
Beverage consumption habits “24/7” among British adults: association with total water intake and energy intake - Gibson and Shirreffs - Nutr J., 2013