CREATE TABLE table_18162 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" TEXT, "Results" TEXT, "Candidates" TEXT)

In what district was Tim Holden the incumbent?
SELECT "District" FROM table_18162 WHERE "Incumbent" = 'Tim Holden'
SELECT "District" FROM "table_18162" WHERE "Incumbent" = 'Tim Holden'