The 50 acres that Cienda Partners last week pitched for Amazon’s $5-billion secondary headquarters lie right at the ‘gateway’ of Oak Cliff.

And a massive rezoning effort placed on the books two years ago makes them prime for that type of development.

The Oak Cliff Gateway, approved by City Council in 2015, allows for buildings up to 20 stories in the areas between Greenbriar Lane and the Trinity River.

Buildings that height must be at least 100 feet apart from each other, and they can’t have a floor plate larger 30,000 square feet. Tall buildings also must be set perpendicular to the river.

The area is zoned as “walkable mixed use,” which requires that “the surrounding area is at least 25 acres and is or will be a mix of dense residential, commercial, and other uses that will achieve  …  increased walkability, reduced vehicular trip generation, and reduced parking demand.”

It could be argued than an Amazon campus would not be “mixed-use,” if it houses mostly offices with no residential or retail components. But the city’s definition for walkable mixed use also states, “These districts are also appropriate for major job centers.”

Cienda bought the old Oak Farms Dairy and an adjacent former pro baseball field, Burnett Field, in 2014. Cities across the nation are trying to woo Washington-based Amazon, which has plans to build a $5-billion regional headquarters for about 50,000 employees.