Explain what Hurston means in the second sentence, "I remember the very day I became colored." What is the effect of the sentence?

In the second sentence of "How It Feels to Be Colored Me," Zora Neale Hurston says, "I remember the very day that I became colored."  She means that she can remember the moment when she began to identify with being a person of color.  In Hurston's early years, she lived in Eatonville, Florida, which was largely a black town.  Few white people moved through town, and those who did liked to watch Hurston "perform" (singing and dancing) on her front porch.  So, Hurston never felt out of place in Eatonville.  However, her family sent her to Jacksonville when she turned 13-years-old so that she could go to school there.  Once Hurston left Eatonville, she began to experience discrimination, and these experiences made her feel "colored."  The sentence in the essay serves to develop the irony in racial identity--Hurston does not inherently feel like a person of color, and she only experiences feeling "colored" when discrimination poses her as an outsider.