When Americans hear the terms “race” or “ethnicity,” certain categories come to mind: “White,” “African American,” “Hispanic,” “Asian.” From filling out the Census Race Question to checking off a box on a job application, these racial categorizations shape both public policy and self-identity. While racial categorizations play an important role in American society, there are certain groups whose identities do not fit into these neatly delineated categories, placing them in the ambiguous space between white and nonwhite. This thesis project examines racial categorization through the lens of three racially ambiguous groups, who each test the boundaries of whiteness and occupy a discrete position outside the lines drawn by present-day racial classifications: (1) Portuguese, (2) Lebanese, and (3) South Asian Indian Americans. Through tracking how these three communities have sought to institutionally express their racial identities over time, this project conducts a qualitative case study to consider: why did the Portuguese, Lebanese, and South Asian Indians—three groups who sought legal classification as white in the early twentieth century—move toward distinct racial self-definitions in the contemporary period, and how does this shift impact the boundaries of whiteness in the United States? This paper finds that shifts in racial classification among these three groups are due to a change in the meaning of whiteness between the early twentieth century and the contemporary period. The transition from overt racially discriminatory laws to covert racially discriminatory laws altered the ways in which whiteness is sustained and enforced, ultimately making it a less appealing label among racially ambiguous groups over time. In assessing this project’s broader implications for where America draws the boundaries of whiteness, this paper introduces a model that depicts whiteness as a concentric circle, arguing that whiteness is better understood as a series of degrees or gradations rather than a bounded category.