Below is the distribution of the Algonquian Language Family from Wikipedia:
They report this language family has 3 branches, but only one is "genetic" (actually related in structure, not just in geography): Eastern Algonquian. However, this is their map of Eastern's distribution:
This sure looks like the exact same map, with everything on the west side (beyond the Iroquoian area) wiped clean.
Is the picture really this simple? Or are there actually some Eastern languages west of that gray area, and/or some non-Eastern languages east of it?
I'm curious, because a distribution with a glaring hole in the middle like that usually indicates that it used to be continuous, and the unrelated languages in the middle came to the area later. However, a lot of times when that happens, it leaves languages on both sides of the hole that are related to each other, and that doesn't look like it happened here. An alternative explanation might be that the Eastern tribes all derived from a single tribe that hopped the mouth of the St. Lawrence, and found lots of land on the coastal areas of the other side that the Iroquois couldn't use as well as they could.