RIP Dr. Nathanson.
75K abortions seem high to me if he stopped in ‘79. RvW was ‘73. He could gave been practicing in a state that legalized it before then (but no sooner than the 60s) or could have been doing them illegally before (ugh) but large numbers didn’t come into play until the 70s IIRC.
Let’s say he did this for ten years - ‘69 to ‘79 - 7500/year?!
To answer your questions: Yes Dr. Nathanson was performing abortions in New York, where it was legal before Roe V Wade legalized it throughout the country. Secondly, note that the article states: “an obstetrician who oversaw the performance of about 75,000 abortions” . He ran the abortion mill. He didn't perform all 75,000 of the abortions personally.
If you read the article, it breaks down the number of abortions he was involved with: “Overall, Nathanson estimated, he presided over 60,000 abortions as director of the facility, instructed fellow practitioners in the performance of 15,000 other abortions, and personally performed about 5,000 abortions, including one on his own child conceived with a girlfriend in the 1960s.”