And some of the projects planned may never get out of the ground. </p><p>Currently 1,230 apartments are under construction in Wilmington and New Hanover County, according to Multifamily Realty Advisors (MRA), which tracks the market in the Triangle and Wilmington.</p><p>Several factors are at work in the booming multifamily market, experts say, including a burgeoning population of seniors, people