Early in the new year, the first of what are expected to be several dozen Democratic presidential wannabes are making preliminary announcements to supporters and the media of their intentions to challenge President Donald Trump in 2020. The first Latino politician out of the gate is Julián Castro, who announced his candidacy on Saturday, January 12. Castro is the 44-year-old former mayor of San Antonio who served as the secretary of housing and urban development during the last three years of the Obama administration. He is the grandson of a Mexican woman who "crossed" to the U.S. in 1922. Almost...