Among Black Voters, a Fervor to Make Their Ballots Count
Many African-Americans around nation, but especially in Florida--galvanized by memory of 2000 election--are determined to have their votes count this time; African-Americans are part of torrent of new voter registrations in swing states like Florida, Pennsylvania, Ohio and elsewhere; black voter participation has been increasing in recent presidential elections; in 2000, 57 percent of eligible black voters turned out, casting one vote for Pres Bush for every nine cast for Al Gore; over last 15 years, rising black middle class has dispersed from cities into integrated suburbs, creating demand for political messages that reflect diverse circumstances of African-Americans; blacks in Florida, mindful of how many black votes were disqualified in 2000, get pledge from Sen John Kerry that he will fight 'until the last dog dies' in event of another contested voting result; photos (M)