I'd give the desert border areas where it was largely empty to the Race. All they'd need to do is bomb a few of the small cities in the Southwest. They couldn't take LA, but they could probably take a good part of Arizona, New Mexico, and some of Texas.
Didn't Larssen have to fight his way passed Race-occupied territory to Seattle? Makes me think that the Race were able to move from Idaho to capture much of the mountains seperating Washington from the east.
The Race were in control of territory all the way to Chicago. Eastern Kentucky should have more Race-held counties. More of Florida should be colored, as it was one of the landing zones.
Indochina was held because the Race avoided the wet jungles, and it was easy to conduct resistance there. There were also no nearby landing areas. In the Peace of Cairo, Indochina was held because the Race didn't want it or control any part of it, the Japanese did, and the other powers wanted as much territory to be taken by humans as possible.