Beth Delta I was the inhabited first planet in its star system.
Paul Stubbs wanted to take Deanna Troi to this planet, to show her the settlement of New Manhattan "as you've never seen it" while drinking some champagne. (TNG: "Evolution")
According to the Star Trek: Star Charts, on the chart "United Federation of Planets I", Beth Delta I was listed as a member planet of the Federation in 2378.
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