When South America experienced the so-called “Pink Tide” in the 2000s, with left and center-left presidents winning elections in multiple countries, Colombia stood as the most notable outlier. The country was controlled by right-wing leader Álvaro Uribe and his allies, a grip on power that lasted for more than two decades. Before that, liberals and conservatives had been taking turns in power for more than a century.
After years of rising anti-establishment sentiment, Colombia made history on Sunday by electing leftist former Bogotá mayor Gustavo Petro as its new president.
Mr. Petro beat populist newcomer Rodolfo Hernández...
