Is this what you want to do?
library(tidyverse)
library(lubridate)
BayAreaData <- data.frame(
stringsAsFactors = FALSE,
Date = c("3/1/2020","3/2/2020",
"3/3/2020","3/4/2020","3/5/2020","3/6/2020","3/7/2020",
"3/8/2020","3/9/2020","3/10/2020","3/11/2020"),
S.Clara = c(7, 9, 11, 14, 20, 24, 32, 37, 43, 43, 48),
S.Mateo = c(1, 2, 2, 2, 2, 2, 2, 2, 9, 9, 15),
SF = c(1, 1, 1, 1, 3, 2, 7, 9, 14, 15, 15),
Alameda = c(1, 1, 2, 2, 2, 3, 3, 3, 3, 5, 5),
ContraCosta = c(3, 3, 4, 4, 4, 7, 7, 12, 12, 13, 13),
Solano = c(6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6),
Sacramento = c(1, 1, 1, 1, 1, 1, 3, 3, 10, 10, 10),
S.Cruz = c(NA, NA, NA, NA, 0, 0, 1, 1, 1, 2, 4),
Marin = c(1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2),
Total = c(21, 24, 28, 31, 39, 46, 62, 74, 100, 105, 118)
)
BayAreaData %>%
mutate(Date = mdy(Date)) %>%
ggplot(aes(x = Date, y = Total)) +
geom_col()

Created on 2020-03-13 by the reprex package (v0.3.0.9001)