Martin County was created in 1925 with the northern portion coming from St. Lucie County and southern portion coming from Palm Beach County. It was named for John W. Martin, Governor of Florida from 1925 to 1929.
When the county was created, the western contour followed the shore of Lake Okeechobee, as did the borders of Glades, Okeechobee, and Hendry counties. Palm Beach County had historically claimed all of the surface of the lake as part of its area, to its benefit for the distribution of state and federal highway funds. The state representative of Martin County, William Ralph Scott of Stuart, initiated a bill to divide the lake among its adjacent counties, creating a more equitable distribution of state funds for road creation and maintenance. All bordering counties confirmed the justice of this change and supported its ratification, with the exception of Palm Beach County. Representatives from Palm Beach County later presented Representative William Scott with a jug of water, signifying "all the water Bill Scott left Palm Beach County." The jug is in the possession of Stuart Heritage.