You can use the following methods to add a vertical line to a histogram in R:

**Method 1: Add Solid Vertical Line at Specific Location**

abline(v=2)

This syntax adds one vertical line to the histogram at x=2.

**Method 2: Add Customized Vertical Line at Specific Location**

abline(v=mean(data), col='red', lwd=3, lty='dashed')

This syntax adds one vertical red dashed line with a width of 3 at the mean value of the histogram.

**Method 3: Add Multiple Customized Vertical Lines**

abline(v=quantile(data, .25), col='red', lwd=3)abline(v=quantile(data, .75), col='blue', lwd=3)

This syntax adds a red vertical line at the first quartile and a blue vertical line at the third quartile of the histogram.

The following examples show how to use each method in practice.

**Example 1: Add Solid Vertical Line at Specific Location**

The following code shows how to create a histogram and add a vertical line at x=2:

#make this example reproducible set.seed(1) #create data data <- rnorm(n=1000, mean=5, sd=2) #create histogram to visualize distribution of data hist(data) #add vertical line at x=2 abline(v=2)

**Example 2: Add Customized Vertical Line at Specific Location**

The following code shows how to create a histogram and add one vertical red dashed line with a width of 3 at the mean value of the histogram:

#make this example reproducible set.seed(1) #create data data <- rnorm(n=1000, mean=5, sd=2) #create histogram to visualize distribution of data hist(data) #add vertical line at mean value abline(v=mean(data), col='red', lwd=3, lty='dashed')

**Example 3: Add Multiple Customized Vertical Lines**

The following code shows how to create a histogram and add a red vertical line at the first quartile and a blue vertical line at the third quartile of the histogram.

#make this example reproducible set.seed(1) #create data data <- rnorm(n=1000, mean=5, sd=2) #create histogram to visualize distribution of data hist(data) #add vertical lines at 1st and third quartiles abline(v=quantile(data, .25), col='red', lwd=3) abline(v=quantile(data, .75), col='blue', lwd=3)

**Additional Resources**

The following tutorials explain how to perform other common tasks in R:

How to Create a Relative Frequency Histogram in R

How to Overlay Normal Curve on Histogram in R

How to Use abline() Function in R