Here's a sample of the imported data - pick a likely 'id' variable...

Obs X Y SEGMENT AFFGEOID10 ALAND10 AWATER10 GEOID10 ZCTA5CE10
1 -75.9944 39.5677 1 8600000US21914 1924479 477175 21914 21914
2 -75.9902 39.5695 1 8600000US21914 1924479 477175 21914 21914
3 -75.9881 39.5724 1 8600000US21914 1924479 477175 21914 21914
4 -75.9893 39.5722 1 8600000US21914 1924479 477175 21914 21914
5 -75.9932 39.5754 1 8600000US21914 1924479 477175 21914 21914