Personal income (based on place of residence) is the sum of:
Net Earnings (adjusted for residence),Transfer Payments, and Dividends, Interest and Rent.

Components of personal income -

Net earnings - the sum of wage and salary disbursements, other labor income, and proprietors' income MINUS personal contributions for social insurance.
Personal dividend income - dividends that are received by individuals and by nonprofit institutions and the dividends that are retained and reinvested by fiduciaries. Dividends are payments in cash or other assets, excluding the corporation's own stock, made by corporations located in the United States or abroad to noncorporate stockholders who are U.S. residents. The state and local area estimates of this component are combined with the estimates of personal interest income and the estimates of rental income of persons in the category dividends, interest, and rent.
Personal interest income - the interest income that is received by persons from all sources. The estimates of personal interest income consist of the estimates of both monetary interest and imputed interest.
Rental income of persons with capital consumption adjustment - the net current-production income of persons from the rental of real property; the imputed net rental income of the owner-occupants of nonfarm dwellings; and the royalties received by persons from patents, copyrights, and the rights to natural resources. It excludes the rental income of persons who are primarily engaged in the real estate business and the imputed net rental income of owner-occupied farm dwellings.
Transfer payments consist of payments to individuals and to nonprofit institutions by Federal, State, and local governments and by businesses.

Other useful definitions:
Per capita personal income is calculated as the total personal income of the residents of an area divided by the population of the area. This statistic is often used as an indicator of the quality of consumer markets and of the economic well-being of the residents of an area. However, the BEA suggests that it be used cautiously.
Personal contributions for social insurance include the contributions or payments by employees, the self-employed, and other individuals to the following social insurance programs: old-age, survivors, and disability insurance (aka social security); hospital insurance; state and local government employee retirement insurance; Federal civilian employee retirement; railroad employee retirement; State unemployment insurance; temporary disability insurance; veterans life insurance; and supplementary medical insurance. Note: these contributions are excluded from personal income by definition (but not excluded from the earnings by industry figures).
Residence of individuals is the county in which they live. Residence of military personnel is the state and county in which they live while they are on military assignment, not their permanent or legal state and county of residence, and the residence of seasonal migrant workers (except those working in Alaska) is the state and county in which they live while they are working, not their usual state and county of residence. The residence of foreign citizens who live in the U.S. and who work for international organizations and foreign embassies and consulates is the country of which they are citizens.

The specific source for these data is the REIS cd/rom (Regional Economic Information System), file CA05.