Left anti join results in rows from only statesPopulationDF if and only if there is no corresponding row in statesTaxRatesDF:

Join the two datasets via the State column as follows:

val joinDF = statesPopulationDF.join(statesTaxRatesDF,
 statesPopulationDF("State") === statesTaxRatesDF("State"), "leftanti")
 %sql
 val joinDF = spark.sql("SELECT * FROM statesPopulationDF LEFT ANTI JOIN
 statesTaxRatesDF ON statesPopulationDF.State = statesTaxRatesDF.State")
scala> joinDF.count
res22: Long = 28
 scala> joinDF.show(5)
 +--------+----+----------+
 | State|Year|Population|
 +--------+----+----------+
 | Alaska|2010| 714031|
 |Delaware|2010| 899816|
 | Montana|2010| 990641|
 | Oregon|2010| 3838048|
 | Alaska|2011| 722713|
 +--------+----+----------+