In a 1967 speech to the annual SCLC leadership convention, Rev. Dr. Martin Luther King Jr. said:

And one day we must ask the question, ‘Why are there forty million poor people in America?’ And when you begin to ask that question, you are raising questions about the economic system, about a broader distribution of wealth. When you ask that question, you begin to question the capitalistic economy.

Have things improved for the poor since he delivered this address? I’m going to use the World Wealth & Income Database to try to answer this question.

suppressPackageStartupMessages(library(dplyr))
suppressPackageStartupMessages(library(stringr))
suppressPackageStartupMessages(library(wid))
suppressPackageStartupMessages(library(ggplot2))

How much of America’s wealth was controlled by its poorest fourty million adults?

totalPopulation <- download_wid(indicators = "npopul",
                                areas = "US",
                                years = 1967,
                                perc = "p0p100",
                                ages = 992,
                                pop = "j")
groupPercentile <- round(100 * 4e7 / totalPopulation$value)

wealthShares <- download_wid(indicators = "shweal",
                             areas = "US",
                             years = 1967:2017,
                             perc = paste0("p", 0:99, "p", 1:100),
                             ages = 992,
                             pop = "j") %>%
  mutate(percentile = as.integer(str_extract(percentile, "(?<=p)([0-9]+)(?=p)")))

groupWealth <- wealthShares %>%
  group_by(year) %>%
  filter(percentile <= groupPercentile) %>%
  summarize(value = sum(value))

groupWealth67 <- groupWealth$value[groupWealth$year == 1967]

In 1967, fourty million adults were 33% of the population. This group together held more debt than assets, controlling -1.2% of the nation’s wealth.

How have the poorest 33% of America fared since King’s speech?

ggplot(groupWealth, aes(year, 100 * value)) +
  geom_line() +
  theme_minimal() +
  scale_x_continuous(breaks = seq(1967, 2017, by = 10)) +
  labs(title = paste0("Wealth share of the poorest ",
                      groupPercentile, "% of Americans"),
       x = "Year",
       y = "Percentage share of wealth",
       caption = "The poor are worse off today than at the time of Dr. King's speech")

This segment of the population is in greater debt now than they were in Dr. King’s time.

How has the richest 1% of the population done since then?

wealthShares %>% 
  filter(percentile == 99) %>%
  ggplot(aes(year, 100 * value)) +
  geom_line() +
  theme_minimal() +
  scale_x_continuous(breaks = seq(1967, 2017, by = 10)) +
  labs(title = paste0("Wealth share of the richest 1% of Americans"),
       x = "Year",
       y = "Percentage share of wealth",
       caption = "The very rich are wealthier today than at the time of Dr. King's speech")

I can’t tell you why there were fourty million poor people in America in 1967, but this gives me an idea of where to go looking for answers.