In the next 20 years, forecasters say we'll get around 4 million more neighbors in the Houston area.HOUSTON, Texas (KTRK) -- The city of Houston could see a population boom in the next 20 years.METRO Next says the area could hit 10 million people by 2040. As of 2015, the population was around 6 million.Forecasters predict much of that growth will happen in the city proper, but may also spread into the Montgomery County area. Report a correction or typo