USpopcenters, cluster, geosphere, ggplot2 (>= 3.3.2), sf (>=
0.9-7), testthat (>= 2.3.2), tibble (>= 3.0.3), tigris (>=
1.0), units
USpopcenters, cluster, geosphere, ggplot2 (>= 3.3.2), sf (>=
0.9-7), testthat (>= 3.0.0), tigris (>= 1.0), units