Oklahoma colored county map is a carefully edited vector graphic from an Adobe Illustrator file, which is available as an editable PDF AI file.
One in A3 JPG file with a resolution of 300 dpi is available. Scale bars provide a visual indication of distance and feature size on the map. The state outline received an independent layer. The file does not contain a gradient fill. Enlarge the image without losing quality. There are no two counties with the same color, which makes the selection easier. The names are only in the fonts of my leading vector program, Adobe Illustrator.