polygon - Keep customized colors with geom_polygon() - Geographic

ggplot2: Elegant Graphics for Data Analysis (3e) - 6 Maps

ggplot2: Elegant Graphics for Data Analysis (3e) - 6 Maps

layouts - Selecting different colors for touching polygons in random color ramp in QGIS? - Geographic Information Systems Stack Exchange

Chapter 8 Creating Maps using ggplot2

Creating R Custom Visuals in Power BI Using ggplot2

Chapter 7 Map R-Gallery-Book

r - Customize colors in ggplot2's geom_polygon using brewer palette - Stack Overflow

The Grammar of Graphics

polygon - Overlaying a polyshape to faceted maps in R with ggplot? - Geographic Information Systems Stack Exchange

polygon - Changing categorized style color simultaneously in QGIS? - Geographic Information Systems Stack Exchange

r - Trouble adding proportional circles on top of symbolized polygon in ggplot2 map - Geographic Information Systems Stack Exchange

r - ggplot2: plotting polygons and points - conflicting scale_color_manual - Stack Overflow

R/ggplot2 adding an additional line/polygon to a choropleth map - Geographic Information Systems Stack Exchange

r - How to create a continuous scale with distinct/custom color and value breaks with ggplot2 map - Geographic Information Systems Stack Exchange