Unlike girl's clothing throughout the 19th Century that can easily be dated from the different styles and construction elements, boy's wear is a totally different story. Everyone loves to see the skeleton suits, but early 19th c children's wear for boys kind of gets defined by that one garment....and there is so much more to what the wore.
Age played a big part in what Mother dressed her sons in~ once past toddling around in gowns like their sisters, they were put into button on trousers and shirts...still clearly child looking~ not at all mature looking in the slightest. I call this the cute stage. What comes next is somewhat of a mystery~ for you cant really say, this year, boys were wearing THIS....as it really did depend on the child, the family's position in society, their geographical location...but generally speaking, American boy's were dressed in full pants, or trousers, shirt and some sort of tunic or jacket~ the older the got, the more fashionably cut the jackets were~ and more accessorized~ as in did young master wear vest and cravat ect ect. Tunics came into play around the 1850s to1860s~ and are not what I am focusing on in this post...What the heck am I trying to introduce you ask? Well, the very tightly fit jackets of the 1840's that most young boys wore around the ages of 9-12ish, exactly like the one worn by the handsome young man in the above daguerreotype.
I would wager to mark that 80% of the 1840 to early 1850 daguerreotypes I have seen with middle aged boys, have them wearing this same tight fitting, long sleeve jacket. They are nearly always dark, meaning the colors vivid~ not necessarily black at all. They are commonly worn with white collar and some type of neck ribbon tied into a bow. What isn't common about them, however, are surviving examples.