While WSID was started by Baltimore mortgage banker Sidney Tinley (hence the 'SID' in the call sign -- and I'm not sure of the original sign-on date) ... if memory serves, Richard Eaton's United Broadcasting purchased the station in 1947.
Eaton, ahead of his time in being a proponent of focused broadcasting to ethnic audiences, introduced programming targeted to Baltimore's black population very early on. R&B and gospel music were staples of the station right up to the early 80s, when 1010 morphed into a 'shadowcast' and/or simulcast of co-owned adult-contemporary FM WYST ('92 Star').
WYST(AM) later fielded various iterations of gold-based programming before transitioning to WERQ(AM) and being sold to Radio One. Today, it's talk WOLB, relaying much of the programming of co-owned WOL(AM) in D.C.