I googled, as I most always do on a frequency search. You can check here also =
Scanner Frequencies - Phone Numbers - IP Addresses
464 MHZ is a business frequency, so it makes sense. At times, one entity will dissolve and pass their radio freqs over to the enity / business that takes over. So it is possible to hear a radio frequency for a business, industry...ect - that is not the reall allocation due to passing of licenses and or radio frequencies.
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Radio Reference is also helpful, but alot of information is submitted by members. =
https://www.radioreference.com/apps/db/?aid=5941
License Search - Advanced License Search
Click on link - Scroll down to licensee & pick Washinton in the space for state - Scroll down further to frequencies and type in 464.475 - go all to bottom of page and on the bottom right side click on geosearch - at geosearch page click Washington as the state and King county. A list of countys appear AFTER the state is clicked on / chosen. Go to bottom of page on right side anc click search.
FF - Medic !!!