Where's the endless loop?

[snippsat]

IT'S NOT AN INFINITE LOOP. It just takes an extremely long time and I'm not sure why... doing further analysis.

Did you read my post about about using loops in Pandas,here is the Post again.

Should not be necessary to make dict of df['DTE'].value_counts()
Work directly with the pandas.Series that value_counts() return.
plt.bar should not be inside a loop.
Something like this.

value_counts = df['DTE'].value_counts()
value_counts = value_counts[value_counts <= 251]
value_counts.plot()