Federal regulators have approved the $31 billion merger of Kansas City Southern railroad with Canadian Pacific. The new railroad, to be named Canadian Pacific Kansas City, will become the first and only railroad to run a direct line between Canada and Mexico — bisecting and hauling freight through the heart of the country, including Kansas City, the second largest freight rail center in the United States. But the merger also will further reduce the number of major North American railroads. The Surface Transportation Board, the primary economic regulator of railroads, announced its decision Wed...