 It has a concurrency of about with FM 37 and passes through the farming community of Happy Union before entering Plainview, where it is known as Date Street.The highway crosses US 70 and then briefly turns to the east along 24th Street before resuming its northward journey.FM 400 has a brief concurrency with FM 788 in northern Hale County; after the two routes separate, FM 400 enters Swisher County, and reaches its northern terminus at FM 145 east of Kress.