*I'm going to be exceedingly clever and run a 5 day series next week and tie back into this post. In the 1930s and 40s it was common for clear channel allocated station to share time. This required that one of the two stations go dark at sunset to avoid crosstalk. This created a legal and practical link between stations that were physically hundreds of miles apart.
In this example I am referring to KJBS-AM and WTAM-AM. WTAM both originally owned by S.E. Lawrence and Theodore Willard, the owners of the Willard Storage Battery Company.
Radios unlike phonographs of the era, required electricity. This was in many cases the first household item that did. These homes, in many cases were not connected to the power grid or in fact lacked a grid to connect to. They were battery powered. So it's not surprising that battery manufacturers sponsored some radio stations and programs.
KJBS went on air as 1271 KFUQ-AM in 1925, changing call letters to KJBS that same year. Their 5 watts covered parts of Frisco from a small studio above their garage on Bush Street. The wussy signal was hammered by KTAB starting a series of moves. More here. In May 1928 the Willard Storage battery Co. sold off WTAM to the Electric Illuminating Co. ending the novelty.
In the 1930 KJBS was granted permission to broadcast at night while WTAM went dark . Previously t KJBS had gone off the air at sunset. as part of thsi new all-night programming KJBS began broadcasting police bulletins on behalf of the SF police Department. (this was before two-way radios.) In 1937 they moved into a space adjacent to the Williard Battery Shop. The sharing was over.
WTAM was KYW-AM briefly and then became WWWE-AM in in 1965 under the ownership of Ohio Communications. Today they're owned by Clear Channel. KJBS is KFAX today, calls they picked up as an all-new station. Today they run completely dull religious talk.