tmap, tidycensus, and choropleth maps for places (cities)

Greetings,

I have select data at the city/place level (not tracts, ZCTAs, etc.), just attribute/variable per city.

I have pulled the places shapefile from tigris and merged the two files and attempted to plot them in R (e.g., using tmap, ggplot2).

However, the geometry information in the places file does not appear to be recognized and I get the following error message: 

File is neither from class sf, stars, Spatial, Raster, nor SpatRaster.

What are alternate ways of getting an appropriate shape file for places or of creating a choropleth map for them?

Thanks,
Saul