Getting rid of unnecessary lines (axes?) in Choroplethr

Question

Whenever I make a choropleth using the Choroplethr package, these unnecessary lines appear. I believe they're axes, but the state_choropleth function shouldn't be printing axes.

Example:

df <- data.frame(region = c("alabama", "alaska", "arizona", "arkansas", "california", "colorado", "connecticut", "delaware", "district of columbia", "florida", "georgia", "hawaii", "idaho", "illinois", "indiana", "iowa", "kansas", "kentucky", "louisiana", "maine", "maryland", "massachusetts", "michigan", "minnesota", "mississippi", "missouri", "montana", "nebraska", "nevada", "new hampshire", "new jersey", "new mexico", "new york", "north carolina", "north dakota", "ohio", "oklahoma", "oregon", "pennsylvania", "rhode island", "south carolina", "south dakota", "tennessee", "texas", "utah", "vermont", "virginia", "washington", "west virginia", "wisconsin", "wyoming"), value = runif(51))
state_choropleth(df)

This is the result: Map with extraneous lines

Can anyone help me get rid of these? I've poked around in the Choroplethr source code but can't seem to identify what these are.

Edit: I'm running Windows 10 Enterprise, R 3.4.2 64-bit, and have installed choroplethr 3.6.1 and ggplot2 2.2.1.

Answer 1

Load ggplot library(ggplot2) and try state_choropleth(df) + theme(panel.border = element_blank()).

This removes the borders for the mainland US. However Alaska and Hawaii still have borders around them.