These companies like to snuggle up close, especially when they are young.

Anyone looking to start a biotech company should pay close attention to this map. It shows the locations of 139 companies closing venture deals in 2013-2015, as reported by Xconomy.

59% of the companies are in the Boston/Cambridge area. 29% are along Route 128. And 12% are near Interstate 495.

Only 4 of the 139 newly venture-backed companies are located in one of the gateway cities, and Lowell is home to 3 of them. Surprisingly, there were no companies in the largest gateway city, Worcester, considered a biotech hot spot.

The Boston area is where investors and entrepreneurs are concentrating their money and their attention despite the efforts of political leaders to spread the benefits of the life science economy around the state. These companies like to snuggle up close, especially when they are young.

Here’s an interactive version of the map. If your company is missing from the map, let us know! We’re adding to it everyday. (Last updated April 23, 2015.)