One method for adding nicely aligned labels to line graphs in ggplot2

labels_on_plots

library(tidyverse)
library(nycflights13)
  
plot_data <- flights %>% 
  filter(carrier %in% c("AA","UA")) %>% 
  count(year, month, carrier)

ggplot(plot_data, aes(x = month, y = n, group = carrier)) +
  geom_path() +
  geom_text(data = filter(plot_data, month == 12), aes(label = carrier), nudge_x = 0.5) +
  scale_x_continuous(limits = c(1,13), breaks = 1:12)