diff --git a/DESCRIPTION b/DESCRIPTION
index 2b606efc..ed053a54 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -17,10 +17,10 @@ Roxygen: list(markdown = TRUE)
 RoxygenNote: 7.1.1
 Biarch: true
 Depends: 
-    R (>= 3.4.0)
+    R (>= 4.0)
 Imports: 
     spdep (>= 1.1-8),
-    sf,
+    sf (>= 1.0-10),
     ggplot2 (>= 3.0.0),
     methods,
     graphics,
diff --git a/R/data.R b/R/data.R
index aba2ad87..0dd70dad 100644
--- a/R/data.R
+++ b/R/data.R
@@ -57,9 +57,9 @@
 #' Mullen, Lincoln A. and Bratt, Jordon. "USABoundaries: Historical and Contemporary Boundaries of the United States of America,"
 #'  Journal of Open Source Software 3, no. 23 (2018): 314, \doi{10.21105/joss.00314}.
 #'
-#' @description A spatial polygons data frame of historical 1910 county boundaries of Florida with aggregated state prison sentencing counts and census data.
+#' @description Simple features (`sf`) with historic (1910) county boundaries of Florida with aggregated state prison sentencing counts and census data.
 #'  Sentencing and population counts are aggregates over the period 1905-1910, where populations were interpolated linearly between decennial censuses of 1900 and 1910.
-#' @format A spatial polygons data frame with the following attributes:
+#' @format Simple features (`sf`)/`data.frame` with the following attributes:
 #' \describe{
 #'  \item{name}{County name}
 #'  \item{wpop}{White population total for years 1905-1910}
diff --git a/R/stan_esf.R b/R/stan_esf.R
index 7b51ad99..9eb10117 100644
--- a/R/stan_esf.R
+++ b/R/stan_esf.R
@@ -175,18 +175,17 @@
 #' log.SSR <- log( SSR, base = 2 )
 #'
 #' # map the log-SSRs
-#' st_as_sf(sentencing) %>%
-#'  ggplot() +
-#'  geom_sf(aes(fill = log.SSR)) +
-#'  scale_fill_gradient2(
-#'    midpoint = 0,
-#'    name = NULL,
-#'    breaks = seq(-3, 3, by = 0.5)
+#'  ggplot(sentencing) +
+#'    geom_sf(aes(fill = log.SSR)) +
+#'    scale_fill_gradient2(
+#'     midpoint = 0,
+#'     name = NULL,
+#'     breaks = seq(-3, 3, by = 0.5)
+#'   ) +
+#'    labs(title = "Log-Standardized Sentencing Ratios",
+#'     subtitle = "log( Fitted/Expected ), base 2"
 #'  ) +
-#'  labs(title = "Log-Standardized Sentencing Ratios",
-#'       subtitle = "log( Fitted/Expected ), base 2"
-#'  ) +
-#'  theme_void()
+#'    theme_void()
 #' }
 #' @export
 #' @md
diff --git a/R/stan_icar.R b/R/stan_icar.R
index c5564174..e70500ae 100644
--- a/R/stan_icar.R
+++ b/R/stan_icar.R
@@ -232,7 +232,7 @@
 #' SSR <- f / sentencing$expected_sents
 #' log.SSR <- log( SSR, base = 2)
 #'
-#' ggplot( st_as_sf(sentencing) ) +
+#' ggplot(sentencing) +
 #'   geom_sf(aes(fill = log.SSR)) +
 #'   scale_fill_gradient2(
 #'    low = "navy",
diff --git a/data-raw/sentencing-data.R b/data-raw/sentencing-data.R
index 78e845f4..d3a416cf 100644
--- a/data-raw/sentencing-data.R
+++ b/data-raw/sentencing-data.R
@@ -1,9 +1,11 @@
 # download sf file with Florida counties and state prison sentencing data, 1905-1910
 library(readr)
+library(sf)
 tf <- tempfile(fileext = ".rds")
 download.file("https://github.com/ConnorDonegan/convict-leasing/raw/master/data/constructed/florida-1910-sp.rds", tf)
 fl <- read_rds(tf)
 fl@data <- fl@data[, c("name", "wpop", "bpop", "sents", "plantation_belt", "pct_ag_1910", "expected_sents")]
 fl@data$sir_raw <- with(fl@data, sents / expected_sents)
-sentencing <- fl
+sentencing <- st_as_sf(fl)
 usethis::use_data(sentencing, overwrite = TRUE)
+
diff --git a/data/sentencing.rda b/data/sentencing.rda
index 322c479e..a17eaa2d 100644
Binary files a/data/sentencing.rda and b/data/sentencing.rda differ