Jack - you have to go back to the 19th Century to understand what seems like an odd street configuration on Parker Avenue. The area had 4 major cemeteries. Point Lobos Avenue (now Geary) ran through and provided access to these "last resting places." The first two blocks of Parker, south of California were the back end of Laurel Hill Cemetery.The Laurel Hill Cemetery property line did not reach Pt. Lobos Ave. but was an odd diagonal from about current Mason to Euclid, so the 100 block was open for residential use (as were short blocks of Wood, Collins, Blake & Boyce). The 200 block of Parker was not quite Odd Fellows Cemetery, because there were two small residential blocks "nibbling" that cemetery's eastern edge, but the south side of Parker did extend past St. Rose Ave. (Anza) to Turk on maps. They laid out Parker wide on both sides of Pt. Lobos Ave. (Geary), probably with the residential potential in mind. But the 0 - 99 block of Parker was a path at the west end of Laurel Cemetery, which wouldn't get residential development until after WWII. The 300 block of Parker had been an undeveloped path between Lone Mountain (some maps show Lone Mt. as Calvary Cemetery, but it never had burials, they were from Masonic to St. Joseph Ave.) and Odd Fellows Cemetery. There had been a "sand-slide" in 1932 that further complicated that block, filling it with sand. Even in the 1950s, it was impassable except for walking. It wasn't until the 1960s, that SF College for Woman put in an access road to a new dorm above Anza, that they built the retaining wall that held the hill from sliding. Maps need to be read carefully, because older ones show "proposed" - like underwater lots, or streets on a grid that were never cut through. It might be hard to visualize, but that is why the 100 and 200 blocks of Parker appear so different from the other ends of that avenue.