Lately I've been reading a lot through the archives of the American Jewish Year Book (published since 1899-1900, initially if I'm not mistaken by the Jewish Publication Society of America and later by the American Jewish Committee). They have a huge number of interesting "blasts from the past," including demographic/cultural/political data, lists of national (and earlier on [pre-1927], local) Jewish organizations, reviews of events in the year in the Jewish world and interesting ``special articles" on numerous topics. One such article, from the 1965 year book, gives an overview of Orthodox Jews in America.
This article, taking up pages 20-96 in that year's Yearbook, is probably worthy of multiple blog posts if I have the time; here's one.
To the extent that [a communal Orthodox structure] existed, however, it was headed by the shtot rov or chief rabbi of each community. This was particularly true outside New York City and Chicago. Cities like Newark, N.J., Boston, Mass., Philadelphia, Pa., Baltimore, Md., Cleveland and Cincinnati, O., Milwaukee, Wis., Springfield, Mass., Rock Island, 111., and Detroit, Mich, each had one rabbi who towered over the Orthodox community; he supervised kosher slaughtering, baking, and the processing of other foods, and presided over the local Jewish court. These were Orthodox leaders par excellence.
Off the top of my head, I can name a handful of these rabbis. For instance, the Baltimore chief rabbi was definitely Rabbi Joseph H. Feldman 1930s-1972 (no real bio of him; his son Emanuel Feldman can in many senses be regarded as the founder of the present Orthodox community in Atlanta and his son Aharon Feldman is the rosh yeshiva of Ner Israel). The Cincinnati chief rabbi was definitely Rabbi Eliezer Silver 1930s-1968, and (I wasn't sure but suspected) apparently the Rav (Rabbi Joseph Soloveitchik) was in factthe Chief Rabbi of Boston 1932-??? (even though he was the rosh yeshiva of RIETS (Yeshiva University's rabbinical school) from 1941 on).. Googling, it seems like Yaakov ben Zion Mendelson in Newark, Rabbi Bernard Levinthal (of B'nai Abraham) in Philadelphia, Binyamin Gittelson in Cleveland