*3.2. Barrier Width*

The variations in barrier width largely do not fall outside of the shoreline position uncertainties, so these results coupled with the aerial photographs should be viewed as qualitative. The average width of the barrier varied over time, ranging from <80 m to >105 m (Figure 8). The narrowest transects were measured in 1883 at transects 39–44 (average 56 m); the widest transects occurred near the groins near the eastern end of the barrier, >220 m at transect 53 in 2011 and 2014. Averaging the width of the barrier between transects 20 and 50 (outside groin influence) showed an increase in width between 1883 and 1963 and a slight decrease in width after 1963. In addition, there was an increase in width between 2004 and 2014 (red triangles, Figure 8). The width of the barrier at transects 26–30 is impacted by the migration and eventual welding of the small spit on the bayside of the barrier (visible in Figures 1, 6 and 9 and the supplemental materials); this is most apparent in the 2011–2014 shorelines. This resulted in an anomalously wide barrier in the 2011–2014 shorelines. The widening at transects 26–30 was not related to overwash and washover fan deposition, which is the inferred process that widened the barrier between 1939 and 1963. Excluding these transects (26–30) shows a decrease in barrier width between 1963 and 2014 (Figure 8).

**Figure 8.** Average width of the barrier based on all transects (red triangles) and transects 20–25 and 31–50 (green triangles). Transects 26–30 were excluded because the dynamics of the small spit on the western bayside of the barrier (see Figure 1, Figure 6, Figure 9 and supplemental materials) alter the barrier width of the 2004–2018 shorelines. See the text for a more detailed discuss of why transects were excluded. The dashed green line represents linear best fit of the data between 1883–1963 and 1963–2016. Error bars are based on the shoreline position uncertainty reported in Table 3.
