What was the first step in Southern politicians' efforts to
legalize segregation?

To disenfranchise African Americans.

Explanation:

The first step in Southern politicians' efforts to legalize segregation was to disenfranchise African Americans by enacting poll taxes and literacy tests.

Many Southern people during this time were racist and wanted to continue the segregation between blacks and whites. They did not want someone that was African American to come into power or run in office, as it may better the lives of African Americans. So they tried their best to enact things to prevent this.

During this time in the South, poll taxes were very common. This made it so in order to vote, you had to pay a fee. Most of the time, African Americans were living in poverty, were being paid less, and did not have the same opportunities as a white person would. This made it harder for them to gain a solid income, so they often times would not have enough money to spare to vote.

Another thing that was very common during this time in the South were literacy tests. This made it so in order to vote, you had to pass a literacy test. Most of the time, African Americans did not or could not obtain an education, so many did not know how to read or write. This prevented many African Americans from being able to vote.  

thing is, i'm afraid, you can't.

the most you can do is log out and never log in again.