Salt Lake City has one of the most unique origin stories of any city in the United States. Not only is the story unusual and well documented, but the plan and layout of the city remain one-of-a-kind. Any observant visitor will note the unusual width of the streets and sometimes hear the persistent myth, attributed to Brigham Young, that they were designed to be large enough to turn around a team of oxen.1 But Salt Lake City has many other unique qualities in its physical plan, which are hard to discover without research. These include its vast extent, the very large blocks, and the very large initial lots, which were driven by religious intentions as well as the model of the Plat of Zion.While many have written about the city's history and even about its plan, inspired by Joseph Smith's 1833 Plat of the City of Zion, I employ the specific technique of urban morphology, which is the analysis and study of the elements of urban form and their changes over time. Urban morphologists compare the current and historical physical form of cities as a way of understanding or verifying urban change, including economic, social, and environmental transformation. This methodology is commonly used to study historic urban plans or buildings, but the methods are also used in contemporary, urban design contexts.2This paper tries to fill out the record by analyzing maps, rather than documents, to follow the subsequent development of Salt Lake City and the impacts of the original plan. Changes in urban form are often an indicator of changes in the broader society, which may include social, economic, and technological transformations. The built form is another record that, in addition to written records, can be consulted to learn about the history of places and people. The concrete existence of urban form, which often is still observable, can be an important counterpoint to misleading or self-promoting documents. The purpose of this study is to help explain the current form of the city and how that form is a result of decisions made in its earliest history. This analysis reveals fascinating patterns of adaptation and preservation, including the persistence of Salt Lake City's famously large streets and extensive grid to the present day. Other adaptations to the original plan are just as common, but were unexpected by the pioneers, like the haphazard lot subdivision or the development of smaller streets inside the large blocks. Many of these changes are positive accidents for the current city's growth, but some are difficult for present-day planners.The origins of Salt Lake City date to 1847 with the arrival of a small band of pioneers led by Brigham Young in the Salt Lake Valley. There, in isolation from their detractors, pioneers of the Church of Jesus Christ of Latter-day Saints (LDS) laid out a beautiful city “foursquare” to the world. It was to be a righteous place to invite the “gathering” of the faithful from all over the world in the last (latter) days before the second coming of Christ.3The geographical calling of the religious sect of Latter-day Saints had been the establishment of a place they called the “City of Zion,” a concept that was both physical and metaphysical. Zion was to be the center of a series of cities and villages organized as righteous and wholesome places where the Saints could live out the principles of their faith.4 In the decades following Great Salt Lake City's founding, Young and his successors orchestrated the establishment of some four hundred settlements across a large swath of the West, stretching from Canada to Mexico.5The location in the mountain West was a kind of spiritual compromise. Although Smith had located the City of Zion very specifically in Independence, Missouri, by divine revelation, the Saints were unable to settle there, due to the violence that frequently erupted when they encountered more traditional Christian settlers. After Smith was murdered by a mob, the Saints, then located in Illinois, determined to find a safer venue for Zion. The highly isolated territory on the western frontier became a suitable alternative to gather the faithful and organize a settlement system. The initial difficulty of reaching the location and its ecological hostility to settlement (a high desert) formed a layer of protection for the persecuted religionists. It also required that pioneers were reliant on and bound to their community, with little support or trade with the outside world.When the earliest pioneers and their leader Brigham Young arrived at the edge of the Salt Lake valley in July 1847, they lost no time in establishing a settlement. Within days they had scouted the land for miles around and identified a place for their new city, laying out first Temple Square and then another 134 blocks in a 9x15 grid, oriented along the cardinal directions (Fig 1a). The primary influence of the grid design was the “Plat of Zion” (Fig 1b), an ideal plan for a mile-square city of 20,000 residents, drawn fourteen years earlier under the supervision of Joseph Smith and intended for Missouri.6 The plan set the dimensions and orientation of blocks, streets and lots, and a central location for temples and other public buildings, but no commercial streets. Smith's “Plat of Zion” was designed to be compact and dense, with small town lots, closely surrounded by agricultural fields that were meant for a daily commute. Smith had designed the City of Zion to hold up to 20,000 people on just one square mile, a density that would require ten to twelve residents for every half-acre house lot.At the time Salt Lake City was founded there were about 17,000 Mormons waiting beyond the Rocky Mountains to follow Young into the Great Basin. Had Young followed the compact Plat of Zion plan, most of them would have been accommodated in the city proper. Instead, the first plat (Plat A) of Salt Lake City was 2.5 square miles, instead of one, but was planned with only 1,080 lots. Plats B and C were laid out the following year. Young greatly altered the dimensions of the lots in the Plat of Zion to reduce the density of the settlement, which would allow more agricultural uses in town. He kept the large dimensions of the blocks and streets, but divided the 10-acre blocks into much larger lots (8 instead of 20) so that each lot was 1.25 acres. This turned out to be a crucial decision. Figure 2 compares the size of blocks and lots in the initial plat of Salt Lake City to the Plat of Zion.In the Plat of Zion, Temple Square was to be located in the center of town. Due to the topography of Salt Lake City, however, Temple Square was not geographically at the center but on the far north where the valley floor meets the foothills to the north and where City Creek divided into two streams. This is apparent on what is believed to be the initial surveyors’ working sheepskin document, recently acquired by the Library of Congress after years of languishing in the attic of a pioneer's descendant.7 Initially, 40 acres (four blocks) were reserved for the temple, storehouses, and other public use. This was quickly scaled back to one city block.8Plat A is a uniform grid of 660 ft x 660 ft blocks (40 rods). Streets, including 20 feet set out for sidewalks on both sides, are 132 ft wide (8 rods). (The street widths were designed to follow the Plat of Zion and not for turning oxen, though the latter was perhaps a practical consequence of the design.) Each block was initially subdivided into eight equal-size lots of 1.25 acres, which is unusually large for a western settlement.9In Salt Lake City, city founders prized self-sufficiency, permitting the planting of vegetable gardens and fruit trees in the early years and erecting barns and animal holding areas, which was a departure from the Plat of Zion directives. As planned, the lots were to contain a single house centered on the lot and set back a uniform distance of 20 feet from the street. Very early regulations also called for shade trees to be planted along the frontage of all lots.10 Plat A allocated three blocks as open spaces, subsequently developed as West High School, Pioneer Park, and Washington Square, the location of the City and County building. These may have been inspired by the squares in William Penn's plan of Philadelphia, which was an important influence on town planning in the United States.In addition to the unusually large dimensions of the blocks and the lots, another remarkable characteristic of the plan is the orientation of the lots. Similar to the original Plat of Zion, the lots were oriented in different directions on every block, creating a basket weave pattern. The intention was privacy for the inhabitants, so that instead of houses facing each other across the street they would face their side yards, presumably planted in garden, providing a green aspect.11After the initial 135 blocks were laid off and distributed, rapid immigration caused two more large plats—Plat B (1848, 64 blocks) and Plat C (1849, 85 blocks)—to be developed in the same pattern.12 In addition to town lots, large agricultural lots (“the Big Fields”) were laid out to the south and west, fulfilling the notion of the agricultural village. Salt Lake City's big fields consisted of five-acre allotments within a large forty-acre block. To the south, it was located between 900 South and 2100 South in present-day Salt Lake City. Figure 3 is a map showing the first three plats and the Big Field to the south, as they existed in about 1855. The initial street plan of the Big Field is reflected in the present-day location of through streets in the Sugar House and Liberty Wells neighborhoods.In the 1870s the church's grip on the city's development was weakened with the influx of new arrivals brought by the transcontinental railroad and mining and commercial opportunities.13 At the same time, the emigration of religious settlers began to wane as church leaders downplayed the “gathering.” Consequently, the city began to accommodate its layout to new peoples and urban uses. These changes can be tracked using the methodology of urban morphology.The method of urban morphology first examines maps of a particular place and then compares that place with itself over time (diachronic analysis) or with other places built in similar time periods (synchronic analysis). The primary data used for urban morphological analysis are maps and field surveys. In this analysis of changes to the form of Salt Lake City I compared individual blocks across time—for example, Block 70 in 1850 to the same location in 2019. I also compare Salt Lake City at its founding in 1847 to Cincinnati, Ohio, in 1802 and Waco, Texas, in 1848. The latter comparison helps to illuminate just how unique Salt Lake City's dimensions and extent were compared to other cities in the United States.The data for this work include historic maps and surveys, Sanborn Fire Insurance Maps, and contemporary GIS data, plans and Google aerial photos.14 These were used to compare the urban form—buildings, lot lines, and streets—in three different blocks of Salt Lake City as it changed over time. The blocks represented different land uses and forms at the end of the study (2019), but would have been identically laid out when first planned. The analysis identified patterns of change that repeatedly occurred in most of the original blocks, and briefly compares them to the Big Field, originally intended for agricultural uses but later developed as suburbs.Three blocks were selected for study. Like all the blocks in these plats, they changed substantially over 160 years. Block 70 is in the densest part of downtown along Main Street, which became the commercial heart of Salt Lake City. Block 47 and Block 22 in Plat B were less intensively developed, being outside the current definition of downtown (images from the analysis of Block 22 are not included here.) These blocks were selected to be compared to each other in order to identify common patterns of adaptation in the early plan. Finally, for these blocks and the others in Plats A and B, the term “Mormon” blocks is used, even though the dimensions and configuration of these blocks were used only in a few other places in other Mormon settlements in the West.15Block 70 is located along Main Street two blocks south of Temple Square (Fig. 4). Today it is a very central area of downtown, with several high-rise buildings. It was a desirable location even in the first years after the settlers arrived.Despite the formal and sacred nature of the ideal plan, the pioneers do not appear to have adhered to it with much religious rigidity, as befits a struggling community. Examining recreated allotment maps of the era it seems that about 25 percent of the large lots were subdivided before being built on.16 This was more common closer to Temple Square. Like all the Mormon blocks, Block 70 originally was surveyed with eight equal lots, but three of the eight lots were subdivided almost immediately (Fig. 5, 1850). Brigham Young himself claimed one of the subdivided lots. Main Street developed quickly into a commercial street, despite the lack of planning for such a use. One year after the initial plat, commercial development was indicated by the subdivision of one of the larger lots into several narrow lots facing Main Street. This pattern is repeated throughout Plat A, and is evident in bird's eye views created in 1870 and 1890.17Thus the Salt Lake City plat lost cohesion from the very beginning. Instead of small houses on large lots surrounded by orchards and barns, the center of the city became urban within a few years, with small lots and multi-story buildings. Certain other plan adaptations began to take shape here that would be constant in all the Mormon blocks, although the areas outside downtown were not as dense. These adaptations are best seen in the 1884 map. Whereas the lots originally created are still visible as subdivisions of the block, the subdivision of the two original lots facing Main Street is more in accordance with commercial patterns prevailing in mid-nineteenth century US cities—lots approximately 25 to 50 feet wide and 165 feet deep. For example, urban lots in Cincinnati created in the same era were 25 feet wide and about 180 feet deep, which allowed for a rear yard.Another pattern is the creation of internal streets on the blocks, which is common on all the plats. On the interior of Block 70 a new, smaller street then called Commercial Street (now Regent Street) essentially doubled the valuable commercial frontage (Fig. 4, 1884). There is even a small alley which runs between the new street and State Street (Plum Alley, Salt Lake City's Chinatown). The frontage has also developed intensely along all the other sides of the block, with less continuity on State Street, probably because of its greater distance from Main Street.Thus the block, only a scant forty years from surveying, has been made over from the agricultural village ideal into a dense, urban place. This corresponds to the timing of the transcontinental railroad and to the growth of mining in the region, both of which brought non-Mormons as well as a new influx of Mormon emigrants to the rapidly growing frontier city.By 1911, the block was completely built out and somewhat redeveloped from 1884, with a new theater and even a “motion picture” house on State Street. Between 1911 and 1950, the eastern half of the block changed little—though a few lots were cleared in the center of the block for parking, the unavoidable twentieth-century land use. On the Main Street half, several smaller buildings were cleared to make way for a large department store and a substantial bank building and a few other tall office structures, as structural steel and elevators rapidly transformed urban buildings across the country.By 1969, the center of the block was replaced with parking and the State Street half of the block was almost obliterated and vacant, with only two substantial new buildings constructed. This coincided with a decades-long decline in Salt Lake City's downtown prior to its current redevelopment.By 2013 the block added a very large central parking garage, but still had some surface parking and a fast food restaurant. An old theater burned and its façade was rescued as a false front for a parking garage. Since 2010 the block has been in active redevelopment so that the map in 2019 includes a 22-story office tower and a 2,500 seat live theater, both located on the north end of the Main Street side of the block. Notably, this very large development is contained within only two of the original lots.Regent Street, being a more intimate scale than any of the original wide streets, was redesigned as a comfortable street for pedestrians and re-opened in 2017. Construction of a 39-story luxury residential tower has started on the southeast corner. Some historic buildings from the 1880s survive along Main Street, and tiny Plum Alley can still be found.Block 47 in Plat B was platted in 1848, only one year after the initial plat. It was also planned with eight lots. Being further distant from the center of town, as defined by proximity to Temple Square, it was slower to develop any substantial density. Consequently, the transformation of the block has been different from Block 70. The patterns observed in this block are very common to all the blocks in Plats B and C.It was necessary from the very beginning to adapt the eight-lot block configuration, because the rapid growth of the city required far more house lots than originally planned. By 1889, we see the first adaptation in all but a few of the Plat B blocks—the subdivision of the outside four lots into many smaller lots, defeating the intended opposite orientation in the original design. These new smaller lots were far closer to standard city lots of the era, although still developed as single family homes, not the urban rowhouses common for US cities. The lots subdivided in this manner had greatly varying widths and sizes with new houses built in different styles after the lot was divided off by its owner. Despite regulation, uniform setbacks were not observed (Fig. 5, 1889).By 1898, the other four lots on the block were also subdivided into narrow, very long lots, leaving much unusable land for urban development in the inside of the block. In subsequent decades, beginning no later than 1911, this problem was handily solved by creating what could be termed “mews”—short dead-end streets with small houses on either side, all within a single original lot. There are many examples of these alleys or mews in the historic plats of Salt Lake City, almost all of them surviving into the late twentieth century and many still extant, although not on this block.In the twentieth century, the automobile began to dominate urban form everywhere. In the Mormon blocks, surface parking areas were often created in the center of the blocks. About the same time, some older houses were destroyed to make way for larger, non-residential uses and apartment blocks, also using the vast interior of the block as parking. Scattered retail strip centers also replaced houses. Many of the smaller, less well-built houses on mews were also destroyed, consolidating lots for larger twentieth-century uses. Although the lack of development pressure kept Block 47 residential through 1950, by 2019, it had become a very heterogeneous mixture of land uses, with building sizes and ages of all types, including a few houses surviving from at least 1898. Like most blocks it also has an internal street—in this case north–south through the block, which evolved over time by joining two dead end alleys.If we compare Salt Lake City with two square grid cities developed in the same era, Waco and Cincinnati, we find another unique quality of the initial plan, which is its very large extent. Waco, Texas, was founded in 1846, just one year before Salt Lake City, on the Brazos River. In contrast to Salt Lake City, Waco's initial blocks (165 ft x 165 ft) and lots were quite small (see Fig. 6). By the late nineteenth century the building lots had been combined and were, like Salt Lake City, very dense. In Cincinnati, founded in 1802 on the Ohio River, the square grid was 400 ft x 400 ft. Like Salt Lake City, the lots were subdivided, not combined, to make a dense fabric by 1890. These two places are more in keeping with the proportions of gridded cities founded in the nineteenth century18. Figure 6 is a startling reminder of both the scale of Salt Lake City's grid and its initial extent. The size of Plats A, B, and C was 1,415 acres, while Cincinnati's original plat was 288 acres, and Waco was only 118 acres (Table 1).Within the Mormon cultural landscape, much larger blocks and streets than in other American cities were common, but these grids seldom followed the dimensions of Salt Lake City or the Plat of Zion.19 Other Mormon settlements more commonly had the grid and street dimensions of Nauvoo, Illinois, which were about half the size of Salt Lake City.20 No initial Mormon plat or foundation was as large as Salt Lake City's.The plan of Salt Lake was designed to create a sense of order. In certain respects, the plan was successful in this regard—and still is. On the other hand, the grid alone cannot create an orderly and gracious pattern of development. For example, people expect a planned city to have recurring patterns of buildings along a street or in a neighborhood, which together create a similar rhythm and feel. This is known as typological continuity, referring to the way houses, for example, are often about the same size, shape, material, setback, and distance apart from neighbors. This was clearly the intention of the Plat of Zion.Instead, Young's large lots encouraged a free-for-all of disorderly subdivision, so that the envisioned genteel agricultural village was destined never to be built. In addition, the plat scale was overwhelming in nearly all respects, as seen in the comparison between cities established in the mid-nineteenth century. Salt Lake City's future was embedded in the rigid block pattern and overly wide streets, coupled with unusual and ill-fitting lot subdivision. These have been troublesome throughout its history, but there are some unexpected benefits.The huge extent of the monotonous grid, for example, is both a blessing and a curse. Usually, cities build out over time with a series of smaller extensions that show a variety of street widths, block sizes, and orientations, often as an adaptation to evolving land uses. Good examples of this include urban developments in New Orleans, Cincinnati, and Denver. In contrast, Salt Lake City's blocks and streets are, for many square miles, all the same. They are undifferentiated in size, and the streets are the same thoroughfare-dimensioned width, in both directions, with no hierarchy. Accordingly, blocks do not organize into identifiable districts, and within the very large plat, only the cardinal street names provide a sense of orientation.On the other hand, the extent of the plan is also an advantage. Many American cities were initially surveyed with a relatively small grid (a mile square was common). Subsequently, growth occurred more haphazardly, with discontinuities in the grid that were exploited to build railroads and, later, highways. In Salt Lake City the generous size of the initial three plats (6.3 square miles) and the Big Field (another 6.5 square miles) has been an accidental blessing that created an extensive, easy-to-navigate, legible framework that still accommodates a very large percentage of the developed area of the city. The continuity of the grid also proved resistant to the destructive overlay of highways and railroads that gutted most American cities in the twentieth century, including Cincinnati and Waco.However, the very large block size has historically been a problem. The large lots within them were subdivided into a very heterogeneous, uneven pattern, with many tiny, ad hoc internal streets. The variation in lot sizes and building sizes, the long period of initial development, and the irregular configuration resulting from many adaptations left the Mormon blocks vulnerable to redevelopment of great variety. Outside of downtown, in the area of Plat B and Plat C, it is not uncommon to find gas stations next to nineteenth-century cottages, or modern high-rise hospitals or schools adjacent to apartment complexes. Almost no block front has a consistent frontage of similar types. The blocks are characterized by multiple land uses and a wide variety of building types, ages, and sizes. At the beginning of the twenty-first century, a large part of the city's central section has no consistent block orientation and no consistent building types, resulting in a hodgepodge along the street and confusing disorder.Still, unlike cities with much smaller grids in North America, the generous ten-acre size of the Mormon blocks has proven more adaptable and flexible in the higher density downtown setting, where very large contemporary building types can easily overwhelm the scale of smaller frameworks in other cities. In Salt Lake, even a large basketball arena can easily fit on a city block, with room to spare, and a generous convention center required the closing of only one street-block. Office buildings and shopping malls are accommodated easily, while there is room for surface parking and parking garages in the blocks’ interior.More recently, the area outside of downtown is under extreme redevelopment pressure as Salt Lake City finds itself in a housing boom. While historic districts in the area provide some protection, heterogeneous twentieth-century development is currently being supplanted by five- to seven-story mixed use apartments with retail. These projects often are made feasible by the original large size of the blocks, even while incorporating the smaller mews streets.The street network also has advantages and disadvantages. The 132-foot wide streets create a rapid and unimpeded flow of traffic, but they are uncomfortable and very difficult to cross for pedestrians, which they must have also been in the nineteenth century. The 660-foot block dimensions tempt pedestrians to jaywalk. Wide streets encourage speeding, causing accidents and endangering bicyclists.Ironically, the greatest sense of order and urban design in the cityscape comes from the very wide tree lawns and ancient trees bordering many of the streets. The wide streets also offer some twenty-first century redevelopment options that take advantage of the excess width. Some streets have been converted into boulevards with wide landscaping in the center. A system of bicycle lanes has been carved out of many of the wide streets, and a few have parking islands in the center. The city's light rail lines run in the center of some streets, bringing a more human dimension without seriously compromising traffic. As these encouraging options play out, the streets become more comfortable for pedestrians and bikes, while at the same time becoming more and more distinct from each other.The presence of small streets and alleys created by early settlers to better utilize the interior of the large blocks creates another opportunity. Because of the basket-weave pattern of the original lots, these streets are discontinuous from block to block, since they almost always form in the north-south or east-west orientation of the original middle lots. Some do not extend through the block, or have a noticeable break in the center. Over 150 of these short streets, mostly public, exist in the area of Plats A and B.These mid-block walkways and streets were unique to Salt Lake City—a separate, secret system overlaying the large streets. Historically and today, they offer pedestrian-scale places that seem a world apart from the wide streets. Partly in response to this research, these have recently been recognized and protected through planning guidelines.21 New mid-block walkways and streets are also encouraged throughout the extent of the original Plats A, B, and C.Even in 1847, it should have been clear to Brigham Young and the early pioneers that the large size of the blocks was unworkable for a city destined to be more than an agricultural village of several hundred. Making do with the size of the lots as given, further subdivisions were common even in the first allotments, despite Young's directive to keep the lots whole. Although the agricultural village concept was successful in much smaller towns across Utah, at least in the nineteenth century, Salt Lake City quickly developed into a dense urban area.22Furthermore, the pioneers had prior experience of town planning in Nauvoo, where the initial platted lots were smaller, as were the blocks and streets. Even these smaller lots were frequently subdivided in the few years that Nauvoo grew into a thriving city. Young himself had visited England and New York City and understood the nature of towns and cities. Joseph Smith greatly admired New York, passed through Cincinnati in the 1830s, and apparently was acutely interested in the creation of a great city.23The Salt Lake City founders’ persistence in the overly generous and unworkable street, block, and lot dimensions is puzzling under these circumstances. By 1859, a new plat in the city (a distinct district now called the Avenues) was created with blocks and streets half the dimensions of the original blocks (330-feet square, with streets sixty-six feet wide). The Avenues’ blocks were initially divided into four lots of 0.6 acres each, very similar to the plat of Nauvoo. It is possible that the slope was a factor, but the haphazard practice of subdivision in the earlier plats probably had an influence in laying out the Avenues. It should be noted that subsequent subdivision of the Avenue's lots was also ubiquitous.The Plat of Zion remains an ideal vision, a compact city surrounded by green fields, all in service to a notion of a close community based on a religiously inspired work ethic, moral code, and communal economy. One might also add that, by modern standards, it would also be a sustainable community: walkable, green, self-sufficient, and dense. But creating the ideal central place of Zion clashed with the immediate and pressing need to accommodate thousands of new residents. The large lots of an agricultural village were never suitable for either purpose, being perhaps a remnant of Young's own discomfort with urbanity.Had Brigham Young actually used the Plat of Zion lot dimensions, there would probably have been more orderly development, since those lots were more in keeping with the cottages of the mid-nineteenth century. We cannot know. Instead, in the Salt Lake City plats, the initial lots were much too large, initiating a frenzy of irregular subdivision that created the internal small streets and irregular buildings of multiple sizes, land uses, and orientation. And because the initial development was not very dense, the extent of the new city had to be expanded dramatically in response to immigration.But it has come to pass that what may have been an ill adaptation in the city's first century and half may now be called advantageous in certain respects. The unique plan of Salt Lake City offers both flexibility and possibility within its rigid and enormous extent. The blocks and small alleys easily accommodate the tremendous growth in the twenty-first century. The wide streets have proven adaptable to a range of multiple public uses, and more may evolve to make the place a walkable, attractive environment. Salt Lake City is a very young city in the scheme of things and its evolution is only beginning. On the whole the plan has offered what all good plans do: a sound framework to guide the evolution of an interesting and varied place.