Without a survey of parents named Smith, we can only speculate about what factors might be responsible for the shortage of Johns in their families. There are no notorious John Smiths in history who might cause parents to avoid the name, as they now avoid Adolf, for example. Creative baby-naming is a well-known feature of African-American culture, and it is worth investigating if this practice has had a negative impact on the number of John Smiths in the U.S. However, only 22 percent of Smiths identified themselves as black in the U.S. census of 2000, while other common surnames showed much higher frequencies (blacks comprise 53 percent of the surname Jackson, 47 percent of Williams, and 38 percent of Thomas). More importantly, Smith and these other common surnames show positive PPF values with other common first names (James and Charles, for example), so there’s evidently no general deficit of conventional first names in combination with surnames that are frequent among African-Americans. So it’s reasonable to conclude that no significant amount of the John Smith shortage can be ascribed to the use of unconventional first names by African-Americans.
But there are two more promising theories. First is the cultural status of John Smith as a “placeholder name.” John and Smith together form a name often used to refer to an archetypal “everyman.” (Another example, of course, is John Doe.) As such, John Smith’s restricted use in the real world may be in the result in part of parents’ wish to avoid this implication of facelessness. Other combinations of common first and last names do not undergo this restriction: John Martin, James Smith, and Mary Williams are overrepresented by 13 to 20 percent.