Looping through rows of a particular column by searching for a string

I imported some data from a txt file using then isolated the columns that are relevant (6 and 11) and renamed from V6 to state and from V11 to population:

customerDataOE <- read.table(file.choose(), 
                               sep = "\t",
                               skip = 2,
                               fill = T)
customerStateAndPopOE <- customerDataOE[,c(6,11)]
colnames(customerStateAndPopOE) <- c("state", "population")

A shortened version of my data looks like this in the environment in RStudio

     state                                      population
[1]  Wisconsin: Milwaukee County                0
[2]  Delaware:                                  59,859
[3]  Washington: King County, Whatcom County    56000
[4]  Washington: Kitsap County, Skagit County   25
[5]  Washington: Island County                  Unknown
[6]  Washington: Snohomish County               1,400

This is in a data.frame class and I want to loop through the state to find if it contains the phrase Washington. If it does, I want to go to population on that same row and add the populations up via a cumulative sum. My end result should be like this: Washington 57425 in a new data.frame

I have tried using grepl but it does not work:

for(i in 1:nrow(customerStateAndPopOE)) {
   if(grepl('Washington', customerStateAndPopOE$state, ignore.case = TRUE))