If you want to sum all of the numeric columns, I would use summarize_if().
library(dplyr)
DF <- data.frame(State = c("AL", "AL", "NY", "NY", "CA"),
County = c("As", "Bo", "Ad", "Cd", "Ya"),
Col3 = c(1, 10, 2,3,4),
Col4 = c(2, 12, 5,4,2),
Col5 = c(1, 13, 6,5,1))
DF %>% group_by(State) %>%
summarize_if(is.numeric, sum)
#> # A tibble: 3 x 4
#> State Col3 Col4 Col5
#> <fct> <dbl> <dbl> <dbl>
#> 1 AL 11 14 14
#> 2 CA 4 2 1
#> 3 NY 5 9 11
Created on 2020-06-13 by the reprex package (v0.3.0)