Have you looked at Indigo Bunting?
I can't find an Indigo Bunting in my bird book.
Check online. It shows blue with the darkest blue on the head and no wing-bars. Are you checking in the 'true' Grosbeaks rather than those of the Finch family called Grosbeak? What book do you use?
Pardon me... that question should have been are you looking at Buntings...my confusion here is that in some books, they are in with Grosbeak and kin.
Sorry for the short answer Frank. A Blue Grosbeak would have very noticeable rufous wing bars which the bird in your photo lacks. The bill is finer than that of a Blue Grosbeak.