The Sunnyside History Project reproduces a 1938 aerial photograph of this stretch. What it shows is not a street. It is rough hillside, no houses, no curbs, no sidewalks. The 1915 Sanborn map has residential lots platted in the surveyor's grid but nothing built on them; the corrected 1950 Sanborn shows those same parcels still empty thirty-five years later. Whatever Sunnyside had become by mid-century, this block had not yet joined it.
The grade explains the vacancy. In "Steep and Leftover," I wrote about the roughly twenty-two-foot elevation change between Monterey Boulevard and Joost Avenue as the force behind Sunnyside's found parks and public stairways. That same slope kept builders off this face of Mangels for decades. The terrain that produced the Detroit Steps also produced this block's long emptiness.
Twenty-two single-family houses line the east side today. The SF Assessor's property tax roll dates nineteen of them to a three-year window: 1960, 1961, and 1962. One predates the cluster by a decade. Two arrived later, in 1967 and 1980. Stand at the Detroit Street corner and look northeast along the block face. Nearly everything you see materialized within a single construction campaign.
The speed of that buildout is immediately apparent in the Assessor data. But speed and uniformity are not the same thing.
300 Mangels
The house at the Detroit Street corner is the block's pioneer. The Assessor dates it to 1951: one story, 1,142 square feet of building on a 2,500-square-foot lot. In the 1938 aerial, this parcel would have been bare hillside. By 1951, someone decided the slope was buildable and committed capital to it alone. For close to a decade, 300 Mangels was the only house on this side of the block. The Western Neighborhoods Project describes Sunnyside filling in stages, its housing eventually including small Victorian cottages joined by 1920s and 1930s stucco homes and later postwar construction. This corner parcel was where the Mangels block's particular stage began.
318 Mangels
The next parcel northeast tells a different story. The Assessor records 318 as built in 1980: two stories, 1,500 square feet on a 2,495-square-foot lot. It is the newest house on the block by eighteen years. Whether it replaced an earlier building or filled a lot that sat empty through the 1960s buildout, the Assessor does not say.
DataSF's metadata notes that the "Year Property Built" field "can be blend of original and newer construction," a caveat worth holding for any parcel where the date seems anomalous.
The physical evidence needs no caveat. From the sidewalk, 318 rises above the one-story roofline that everything around it establishes. Where the neighboring houses sit low against the hillside, presenting a single level to the street, this one asserts a second story. The break is unmistakable.
322–334 Mangels
Beginning at 322, four consecutive houses share a construction year of 1960. All are one-story dwellings on lots of 2,495 square feet. Their building areas diverge: 322 is 1,275 square feet, 326 and 330 are each 1,065, and 334 is 1,441. Same year, same lot dimensions, different footprints. From the sidewalk, though, the difference is subtle. On lots this narrow, the variation plays out mostly in depth, not width. The two 1,065-square-foot houses read as a pair, sitting at the same scale against the street. The 1,441-square-foot house does not look dramatically larger from the front; it extends farther back on its lot, a difference visible from the side or from above but not from the facing sidewalk. The Assessor reveals what the facade keeps to itself.
Whether these four represent a single builder offering multiple floor plans or two builders working adjacent parcels in the same season, the Assessor cannot resolve. What it does show is that the block's buildout began here, a few houses at a time, one year before the main wave.
338–342 Mangels
Two houses break the chronological sequence. At 338 and 342, the Assessor records a construction year of 1962, one year after the thirteen houses that fill the rest of the block. Both are one-story. Both are 1,230 square feet. Both sit on 2,495-square-foot lots. The matching dimensions suggest a single builder completing a pair after the main campaign had passed. They are the block's last deliberate repetition.
346–394 Mangels
The thirteen houses from 346 to 394 are the block face's central fact. All carry a construction year of 1961. All are single-family dwellings. All sit on lots between 2,495 and 2,500 square feet. All were designed for the automobile from the start, their ground floors built to accommodate garages rather than retrofitted later.
Within that uniformity, the variation is considerable. The smallest houses, 346 and 354, are 918 square feet each. The largest, 358, is 1,855 square feet, more than double their size on an almost identical lot. Between those extremes the building areas follow no neat gradient. They jump: 1,315 at 350, then 918 at 354, then 1,855 at 358, then 1,178 at both 362 and 366. The pattern suggests a builder offering a catalog of models rather than repeating a single plan, or possibly multiple builders working within the same subdivision simultaneously. Without the original tract map or subdivision filing, the Assessor data cannot distinguish between these possibilities.
Physically, the result is legible from the sidewalk. Walk this stretch slowly and you can see the original rhythm beneath the accumulated individuality: same setback, same lot width, different house. At 378 and 382, the building area is 1,071 square feet each, and the family resemblance holds. They sit at the same height, present the same proportions to the street, share the low-slung profile that postwar single-story construction gave to graded hillside lots. Sixty-five years of different paint choices, different plantings in the narrow front setbacks, different screen doors and mailbox placements have not erased the kinship. At 386 and 390, the areas diverge more sharply (1,660 and 1,773), and the resemblance loosens. The block, in this stretch, carries a recognizable cadence without monotony, because decades of habitation have given each house its own texture while the lot lines hold the original spacing.
Two houses within the 1961 group rise to two stories: 370 and 374, with building areas of 1,776 and 1,665 square feet. They sit side by side near the Edna end of the block, and from the sidewalk they are the most visible departure from the prevailing horizontal line. Where the one-story houses settle into the hillside, presenting their rooflines below the sightline of a person standing across the street, 370 and 374 push above it. The additional story is where the extra square footage lives; at the street, their lot frontages are no wider than their neighbors'.
400 Mangels
At the Edna Street corner, 400 Mangels sits on a different Assessor block (3064, where the rest of the face is 3063) and carries a construction year of 1967. One story, 1,570 square feet, 2,500-square-foot lot. Six years after the main campaign, the block's last gap filled in. The buildout that began with a single house in 1951 was complete.
What the sequence shows
A single house on this block face would tell you it was built around 1961 and is a modest postwar dwelling. The full sequence tells you more. The hillside resisted development for decades. Someone committed in 1951. The rest followed in a rush, and even the rush had phases: four houses in 1960, thirteen in 1961, two more in 1962, a straggler in 1967. Construction-date clusters reveal the campaign's timing. Breaks in the one-story roofline, at 318 and at 370–374, mark the parcels where something different happened. Matched pairs of identical square footage suggest a single hand at work; sharp jumps in building area on adjacent lots suggest multiple builders or a catalog of choices.
This is not the Sunnyside of the Edwardian cottages along Hearst or the stucco homes near Monterey Boulevard. Those blocks were built in the streetcar era, on gentler terrain, by builders working within earlier residential conventions. The Mangels block belongs to Sunnyside's second act: the postwar infill that filled the steeper, rougher ground the earlier builders had passed over. Its houses were designed for the automobile from the start, built on graded lots wide enough for integrated garages, at a moment when car ownership was assumed rather than accommodated after the fact.
You read the block from the sidewalk, one house at a time, if you bring the dates.
East side of Mangels Avenue, Detroit to Edna: Assessor data
All lots are 2,495–2,500 sq ft. Source: SF Assessor's property tax roll.
| Address | Year Built | Stories | Building Area (sq ft) |
|---|---|---|---|
| 300 | 1951 | 1 | 1,142 |
| 318 | 1980 | 2 | 1,500 |
| 322 | 1960 | 1 | 1,275 |
| 326 | 1960 | 1 | 1,065 |
| 330 | 1960 | 1 | 1,065 |
| 334 | 1960 | 1 | 1,441 |
| 338 | 1962 | 1 | 1,230 |
| 342 | 1962 | 1 | 1,230 |
| 346 | 1961 | 1 | 918 |
| 350 | 1961 | 1 | 1,315 |
| 354 | 1961 | 1 | 918 |
| 358 | 1961 | 1 | 1,855 |
| 362 | 1961 | 1 | 1,178 |
| 366 | 1961 | 1 | 1,178 |
| 370 | 1961 | 2 | 1,776 |
| 374 | 1961 | 2 | 1,665 |
| 378 | 1961 | 1 | 1,071 |
| 382 | 1961 | 1 | 1,071 |
| 386 | 1961 | 1 | 1,660 |
| 390 | 1961 | 1 | 1,773 |
| 394 | 1961 | 1 | — |
| 400 | 1967 | 1 | 1,570 |