Want to increase the GDP? Easy. Let more immigrants in. Lena Groeger for ProPublica:

In an analysis for ProPublica, Adam Ozimek and Mark Zandi at Moody’s Analytics, an independent economics firm, estimated that for every 1 percent increase in U.S. population made of immigrants, GDP rises 1.15 percent. So a simple way to get to Trump’s 4 percent GDP bump? Take in about 8 million net immigrants per year. To show you what that really looks like, we’ve charted the effect below. You can see for yourself what might happen to the economy if we increased immigration to the highest rates in history or dropped it to zero – and everything in between.

The interactive in the article lets you pose the what-if with various immigration rates. Give it a try.