Planning & Walkability Analysis

• Geographic Scale Issues (Census Block Groups)

The NWI is calculated at the census block group level, which can be quite large or heterogeneous. This introduces two problems:

• Local walkable pockets within a block group may be averaged with non-walkable areas, lowering the score.
• Conversely, areas with poor walking environments but nearby amenities can score higher than actual conditions suggest.
  This spatial aggregation can mask fine-grained variations that matter to pedestrians (Steuteville, 2019).

Another limitation of using Census block group–level data is that many municipalities—particularly very small or rural jurisdictions—are too small to contain a block group centroid. In some cases, multiple municipalities fall within a single block group, making it difficult to assign distinct and representative walkability scores to each jurisdiction.

Similar issues arise at the neighborhood scale. For example, users familiar with Columbus, Ohio, may notice that Wolfe Park is not included in the neighborhood-level interactive maps. Due to its very small geographic footprint, this neighborhood was excluded from the analysis. A comparable issue occurs in Dallas, Texas, where larger districts such as Northeast Dallas can be further subdivided into distinct neighborhoods, including Deep Ellum, Bryan Place, and Lower Greenville. Downtown Dallas presents a similar challenge, as it can be divided into eight subdistricts: the Arts District, City Center District, Convention Center District, Farmers Market District, Government District, Main Street District, Reunion District, and the West End Historic District.

At present, Fort Worth has not been analyzed at the neighborhood scale because many of its neighborhoods are too small to be meaningfully evaluated using block group–level data. While Census block–level data would offer greater spatial precision and potentially resolve some of these issues, it introduces additional methodological challenges due to the extremely small size of individual blocks. These challenges can replicate the same aggregation and interpretation issues observed with block groups in dense urban environments, which are discussed in the following section.

• Less Effective in Very Dense Urban Contexts

Some analysts note the Index may undervalue extremely dense, highly walkable cities because:

• Block groups in dense cities are geographically small and may lack sufficient land-use diversity within the block group itself (even though adjacent areas are highly walkable).
  This can make scores less intuitive in downtown or urban core environments (America Walks, n.d.).

• Composite Nature Can Mask Key Variables

Because the Index combines different variables into a single score:

• One dominant component (e.g., transit proximity) can drive the score even if others (like intersection density) are weak.
• This makes it hard to interpret which specific elements most influence the score in any given place (Pinski & McCarthy, 2023).

As noted previously with the example of International Market Place in Indianapolis—where an area is classified as highly walkable despite offering poor pedestrian conditions—the opposite limitation can also occur. Some of the most genuinely walkable urban environments receive relatively low National Walkability Index (NWI) scores. This outcome reflects the Index’s reduced effectiveness in very dense urban contexts and the challenges associated with aggregating multiple variables into a single composite score. New York City provides a clear illustration of this limitation.

When evaluated alongside other U.S. municipalities, New York City exhibits a relatively low overall NWI score and is classified only as above average in walkability. This result is driven primarily by low intersection density values, particularly within Manhattan. At face value, this finding appears counterintuitive, as Manhattan is widely recognized as one of the most walkable urban environments in the United States.

The discrepancy arises from the extremely small size of many Census block groups in midtown and upper Manhattan. In numerous cases, these block groups encompass only a single city block and therefore contain no intersections within their boundaries. This pattern became evident during neighborhood-level analysis. While lower Manhattan appears less affected by this issue, the prevalence of small block groups elsewhere in the borough substantially suppresses intersection density scores and, by extension, the overall NWI score for the city.

Although employment mix and employment–household mix scores are also relatively low for New York City, a comprehensive assessment of these variables is still in progress. At the time of writing, analysis has been completed only for the boroughs of Staten Island and Manhattan. Further evaluation of the remaining boroughs is expected to provide greater insight into the factors influencing these components of the Index.

• Irregular Data Updates / Data Currency

The publicly released NWI is based on datasets from around 2017–2020, meaning:

• scores may lag behind current land-use or infrastructure changes.
• trends (e.g., new mixed-use developments or new transit service) may not be reflected until a future update (America Walks, n.d.).