It is difficult to determine the most common white last name as it varies depending on geographic location, cultural history, and migration patterns. However, in the United States, there are several last names that are particularly common among white Americans.

According to the United States Census Bureau, the top five most common white last names in the United States are Smith, Johnson, Williams, Brown, and Jones. These names have been among the most common for many decades and are still widely prevalent today.
The origins of these last names are varied, but many can be traced back to the United Kingdom or other European countries. For example, the name Smith was traditionally a surname for a metalworker or blacksmith, while Johnson was originally a patronymic name meaning “son of John.”
Other common white last names in the United States include Miller, Davis, Garcia, Rodriguez, Martinez, Hernandez, and Gonzalez. These names often reflect the diversity of the country’s population, with many coming from Hispanic or Latino heritage.
It is also worth noting that the prevalence of certain last names can be influenced by factors such as immigration patterns, intermarriage, and social status. For example, certain last names may be more common among specific immigrant groups, while others may be associated with higher social or economic status.
In conclusion, while it is difficult to determine the most common white last name, several names, including Smith, Johnson, Williams, Brown, and Jones, have consistently ranked among the top for many decades. The prevalence of these names reflects the diverse cultural and historical influences that have shaped the United States.