This year, the US will deliver 50% more apartments than 2015, topping 320,000 units, according to a new study by RentCafé. And 70,000 of those are between Houston, Dallas, Austin and San Antonio—Texas' big four comprise 22% of the country's apartments underway.

Houston and Dallas top the list of metros with the most deliveries at 26,000 and 23,000, respectively, according to Yardi Matrix data. Austin comes in sixth with 14,000 units, and San Antonio comes in 16th with 7,000 units.

Surprising to no one, Texas also dominates on the list of fastest-growing metro areas. (Have you heard of a little town called Plano?)

One-bedrooms account for more than half of all units in the pipeline. And studios continue to decline in popularity, accounting for just 1% of inventory in Houston, 4% in Dallas and 3% in Austin.