  Sensitive measurements of the interstellar gas-phase oxygen abundance have
revealed a slight oxygen deficiency ($\sim$ 15%) toward stars within 500 pc of
the Sun as compared to more distant sightlines. Recent $FUSE$ observations of
the interstellar gas-phase nitrogen abundance indicate larger variations, but
no trends with distance were reported due to the significant measurement
uncertainties for many sightlines. By considering only the highest quality
($\geq$ 5 $\sigma$) N/O abundance measurements, we find an intriguing trend in
the interstellar N/O ratio with distance. Toward the seven stars within $\sim$
500 pc of the Sun, the weighted mean N/O ratio is 0.217 $\pm$ 0.011, while for
the six stars further away the weighted mean value (N/O = 0.142 $\pm$ 0.008) is
curiously consistent with the current Solar value (N/O =
0.138$^{+0.20}_{-0.18}$). It is difficult to imagine a scenario invoking
environmental (e.g., dust depletion, ionization, etc.) variations alone that
explains this abundance anomaly. Is the enhanced nitrogen abundance localized
to the Solar neighborhood or evidence of a more widespread phenomenon? If it is
localized, then recent infall of low metallicity gas in the Solar neighborhood
may be the best explanation. Otherwise, the N/O variations may be best
explained by large-scale differences in the interstellar mixing processes for
AGB stars and Type II supernovae.
