To succeed in the U.S. economy, companies must constantly adapt to changing conditions. Some of the nation’s largest corporations — conglomerates such as General Electric (NYSE: GE), Exxon Mobil (NYSE: XOM), and Wal-Mart (NYSE: WMT) — have always dominated. Still, for many American consumers, the landscape of companies in the United States has shifted over the course of their lifetimes.

24/7 Wall St. reviewed annual revenue figures for the nation’s largest 500 companies in each year from 1955 to 2015 — figures came from business magazine Fortune. General Motors (NYSE: GM) was the nation’s largest company throughout the 1950s, ‘60s, and part of the ‘70s. Exxon Mobil edged out the automaker giant in 1975, but GM returned to the No. 1 position periodically in subsequent years. Since 2001, Wal-Mart or Exxon Mobil has occupied the top spot. The global retailing giant reported revenues of $478.6 billion in its most recent fiscal year, making it the world’s largest company by revenue. While falling oil and gas prices have hurt Exxon Mobil’s bottom line substantially, its latest annual revenue of $268.9 billion is well above that of most U.S. companies.

Because these are the largest companies in the country, any meaningful deterioration in size usually takes years, if not decades. Gradual changes in size over the longer term among fortune 500 companies reflects larger trends in the U.S. economy. For example, the decline of automobile company GM and the rise of retailer Wal-Mart over the past 50 years reflects the decline of American manufacturing and the rise of the service sector over that time.

Click here to see the biggest company the year you were born.

Compared to the middle of the 20th century, today there are fewer assembling, operating, transporting, and other production jobs. Meanwhile, the number of child care, food service, cleaning, and other service sector jobs has skyrocketed. In a study of low-skill service jobs in the U.S. labor market, MIT economists David Autor and David Dorn found that as a share of the workforce, employment in production jobs fell by 25.8% from 1980 through 2005, while service occupations grew by 53.2% over that period.

To identify the largest companies in the year you were born, 24/7 Wall St. reviewed annual revenue figures for companies on the Fortune 500 each year from 1955 through 2015. For every year since 1955, the top five companies by revenue are listed.

1. General Motors: $9.82 billion
2. Exxon Mobil: $5.66 billion
3. U.S. Steel: $3.25 billion
4. General Electric: $2.96 billion
5. Esmark: $2.51 billion

1. General Motors: $12.44 billion
2. Exxon Mobil: $6.27 billion
3. Ford Motor: $5.59 billion
4. U.S. Steel: $4.10 billion
5. Chrysler: $3.47 billion

1. General Motors: $10.80 billion
2. Exxon Mobil: $7.13 billion
3. Ford Motor: $4.65 billion
4. U.S. Steel: $4.23 billion
5. General Electric: $4.09 billion

1. General Motors: $10.99 billion
2. Exxon Mobil: $7.83 billion
3. Ford Motor: $5.77 billion
4. U.S. Steel: $4.41 billion
5. General Electric: $4.34 billion

1. General Motors: $9.52 billion
2. Exxon Mobil: $7.54 billion
3. Ford Motor: $4.13 billion
4. General Electric: $4.12 billion
5. U.S. Steel: $3.47 billion

1. General Motors: $11.23 billion
2. Exxon Mobil: $7.91 billion
3. Ford Motor: $5.36 billion
4. General Electric: $4.35 billion
5. U.S. Steel: $3.64 billion

1. General Motors: $12.74 billion
2. Exxon Mobil: $8.04 billion
3. Ford Motor: $5.24 billion
4. General Electric: $4.20 billion
5. U.S. Steel: $3.70 billion

1. General Motors: $11.40 billion
2. Exxon Mobil: $8.44 billion
3. Ford Motor: $6.71 billion
4. General Electric: $4.46 billion
5. Mobil: $3.32 billion

1. General Motors: $14.64 billion
2. Exxon Mobil: $9.54 billion
3. Ford Motor: $8.09 billion
4. General Electric: $4.79 billion
5. Mobil: $3.93 billion

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1. General Motors: $16.50 billion
2. Exxon Mobil: $10.26 billion
3. Ford Motor: $8.74 billion
4. General Electric: $4.92 billion
5. Mobil: $4.35 billion

1. General Motors: $17.00 billion
2. Exxon Mobil: $10.82 billion
3. Ford Motor: $9.67 billion
4. General Electric: $4.94 billion
5. Mobil: $4.50 billion

1. General Motors: $20.73 billion
2. Ford Motor: $11.54 billion
3. Exxon Mobil: $11.47 billion
4. General Electric: $6.21 billion
5. Chrysler: $5.30 billion

1. General Motors: $20.21 billion
2. Ford Motor: $12.24 billion
3. Exxon Mobil: $12.19 billion
4. General Electric: $7.18 billion
5. Chrysler: $5.65 billion

1. General Motors: $20.03 billion
2. Exxon Mobil: $13.27 billion
3. Ford Motor: $10.52 billion
4. General Electric: $7.74 billion
5. Chrysler: $6.21 billion

1. General Motors: $22.76 billion
2. Exxon Mobil: $14.09 billion
3. Ford Motor: $14.08 billion
4. General Electric: $8.38 billion
5. Chrysler: $7.45 billion

1. General Motors: $24.30 billion
2. Exxon Mobil: $14.93 billion
3. Ford Motor: $14.76 billion
4. General Electric: $8.45 billion
5. International Business Machines: $7.20 billion

1. General Motors: $18.75 billion
2. Exxon Mobil: $16.55 billion
3. Ford Motor: $14.98 billion
4. General Electric: $8.73 billion
5. International Business Machines: $7.50 billion

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1. General Motors: $28.26 billion
2. Exxon Mobil: $18.70 billion
3. Ford Motor: $16.43 billion
4. General Electric: $9.43 billion
5. International Business Machines: $8.27 billion

1. General Motors: $30.44 billion
2. Exxon Mobil: $20.31 billion
3. Ford Motor: $20.19 billion
4. General Electric: $10.24 billion
5. Chrysler: $9.76 billion

1. General Motors: $35.80 billion
2. Exxon Mobil: $25.72 billion
3. Ford Motor: $23.02 billion
4. Chrysler: $11.77 billion
5. General Electric: $11.58 billion

1. Exxon Mobil: $42.06 billion
2. General Motors: $31.55 billion
3. Ford Motor: $23.62 billion
4. Texaco: $23.26 billion
5. Mobil: $18.93 billion

1. Exxon Mobil: $44.87 billion
2. General Motors: $35.73 billion
3. Texaco: $24.51 billion
4. Ford Motor: $24.01 billion
5. Mobil: $20.62 billion

1. Exxon Mobil: $48.63 billion
2. General Motors: $47.18 billion
3. Ford Motor: $28.84 billion
4. Texaco: $26.45 billion
5. Mobil: $26.06 billion

1. General Motors: $54.96 billion
2. Exxon Mobil: $54.13 billion
3. Ford Motor: $37.84 billion
4. Mobil: $32.13 billion
5. Texaco: $27.92 billion

1. General Motors: $63.22 billion
2. Exxon Mobil: $60.34 billion
3. Ford Motor: $42.78 billion
4. Mobil: $34.74 billion
5. Texaco: $28.61 billion

1. Exxon Mobil: $79.11 billion
2. General Motors: $66.31 billion
3. Mobil: $44.72 billion
4. Ford Motor: $43.51 billion
5. Texaco: $38.35 billion

1. Exxon Mobil: $103.14 billion
2. Mobil: $59.51 billion
3. General Motors: $57.73 billion
4. Texaco: $51.20 billion
5. Chevron: $40.48 billion

1. Exxon Mobil: $108.11 billion
2. Mobil: $64.49 billion
3. General Motors: $62.70 billion
4. Texaco: $57.63 billion
5. Chevron: $44.22 billion

1. Exxon Mobil: $97.17 billion
2. General Motors: $60.03 billion
3. Mobil: $59.95 billion
4. Texaco: $46.99 billion
5. Ford Motor: $37.07 billion

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1. Exxon Mobil: $88.56 billion
2. General Motors: $74.58 billion
3. Mobil: $54.61 billion
4. Ford Motor: $44.46 billion
5. International Business Machines: $40.18 billion

1. Exxon Mobil: $90.85 billion
2. General Motors: $83.89 billion
3. Mobil: $56.05 billion
4. Ford Motor: $52.37 billion
5. Texaco: $47.33 billion

1. General Motors: $96.37 billion
2. Exxon Mobil: $86.67 billion
3. Mobil: $55.96 billion
4. Ford Motor: $52.77 billion
5. International Business Machines: $50.06 billion

1. General Motors: $102.81 billion
2. Exxon Mobil: $69.89 billion
3. Ford Motor: $62.72 billion
4. International Business Machines: $51.25 billion
5. Mobil: $44.87 billion

1. General Motors: $101.78 billion
2. Exxon Mobil: $76.42 billion
3. Ford Motor: $71.64 billion
4. International Business Machines: $54.22 billion
5. Mobil: $51.22 billion

1. General Motors: $121.09 billion
2. Ford Motor: $92.45 billion
3. Exxon Mobil: $79.56 billion
4. International Business Machines: $59.68 billion
5. General Electric: $49.41 billion

1. General Motors: $126.97 billion
2. Ford Motor: $96.93 billion
3. Exxon Mobil: $86.66 billion
4. International Business Machines: $63.44 billion
5. General Electric: $55.26 billion

1. General Motors: $125.13 billion
2. Exxon Mobil: $105.89 billion
3. Ford Motor: $98.28 billion
4. International Business Machines: $69.02 billion
5. Mobil: $58.77 billion

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1. General Motors: $123.78 billion
2. Exxon Mobil: $103.24 billion
3. Ford Motor: $88.96 billion
4. International Business Machines: $65.39 billion
5. General Electric: $60.24 billion

1. General Motors: $132.78 billion
2. Exxon Mobil: $103.55 billion
3. Ford Motor: $100.79 billion
4. International Business Machines: $65.10 billion
5. General Electric: $62.20 billion

1. General Motors: $133.62 billion
2. Ford Motor: $108.52 billion
3. Exxon Mobil: $97.83 billion
4. International Business Machines: $62.72 billion
5. General Electric: $60.82 billion

1. General Motors: $154.95 billion
2. Ford Motor: $128.44 billion
3. Exxon Mobil: $101.46 billion
4. Wal-Mart Stores: $83.41 billion
5. AT&T: $75.09 billion

1. General Motors: $168.83 billion
2. Ford Motor: $137.14 billion
3. Exxon Mobil: $110.01 billion
4. Wal-Mart Stores: $93.63 billion
5. AT&T: $79.61 billion

1. General Motors: $168.37 billion
2. Ford Motor: $146.99 billion
3. Exxon Mobil: $119.43 billion
4. Wal-Mart Stores: $106.15 billion
5. General Electric: $79.18 billion

1. General Motors: $178.17 billion
2. Ford Motor: $153.63 billion
3. Exxon Mobil: $122.38 billion
4. Wal-Mart Stores: $119.30 billion
5. General Electric: $90.84 billion

1. General Motors: $161.32 billion
2. Ford Motor: $144.42 billion
3. Wal-Mart Stores: $139.21 billion
4. Exxon Mobil: $100.70 billion
5. General Electric: $100.47 billion

1. General Motors: $189.06 billion
2. Wal-Mart Stores: $166.81 billion
3. Exxon Mobil: $163.88 billion
4. Ford Motor: $162.56 billion
5. General Electric: $111.63 billion

1. Exxon Mobil: $210.39 billion
2. Wal-Mart Stores: $193.30 billion
3. General Motors: $184.63 billion
4. Ford Motor: $180.60 billion
5. General Electric: $129.85 billion

1. Wal-Mart Stores: $219.81 billion
2. Exxon Mobil: $191.58 billion
3. General Motors: $177.26 billion
4. Ford Motor: $162.41 billion
5. Enron: $138.72 billion

1. Wal-Mart Stores: $246.53 billion
2. General Motors: $186.76 billion
3. Exxon Mobil: $182.47 billion
4. Ford Motor: $163.63 billion
5. General Electric: $131.70 billion

1. Wal-Mart Stores: $258.68 billion
2. Exxon Mobil: $213.20 billion
3. General Motors: $195.65 billion
4. Ford Motor: $164.50 billion
5. General Electric: $134.19 billion

1. Wal-Mart Stores: $288.19 billion
2. Exxon Mobil: $270.77 billion
3. General Motors: $193.52 billion
4. Ford Motor: $172.23 billion
5. General Electric: $152.36 billion

1. Exxon Mobil: $339.94 billion
2. Wal-Mart Stores: $315.65 billion
3. General Motors: $192.60 billion
4. Chevron: $189.48 billion
5. Ford Motor: $177.21 billion

1. Wal-Mart Stores: $351.14 billion
2. Exxon Mobil: $347.25 billion
3. General Motors: $207.35 billion
4. Chevron: $200.57 billion
5. ConocoPhillips: $172.45 billion

1. Wal-Mart Stores: $378.80 billion
2. Exxon Mobil: $372.82 billion
3. Chevron: $210.78 billion
4. General Motors: $182.35 billion
5. ConocoPhillips: $178.56 billion

1. Exxon Mobil: $442.85 billion
2. Wal-Mart Stores: $405.61 billion
3. Chevron: $263.16 billion
4. ConocoPhillips: $230.76 billion
5. General Electric: $183.21 billion

1. Wal-Mart Stores: $408.21 billion
2. Exxon Mobil: $284.65 billion
3. Chevron: $163.53 billion
4. General Electric: $156.78 billion
5. Bank of America Corp.: $150.45 billion

1. Wal-Mart Stores: $421.85 billion
2. Exxon Mobil: $354.67 billion
3. Chevron: $196.34 billion
4. ConocoPhillips: $184.97 billion
5. Fannie Mae: $153.83 billion

1. Exxon Mobil: $452.93 billion
2. Wal-Mart Stores: $446.95 billion
3. Chevron: $245.62 billion
4. ConocoPhillips: $237.27 billion
5. General Motors: $150.28 billion

1. Wal-mart Stores: $469.16 billion
2. Exxon Mobil Corporation: $449.89 billion
3. Chevron Corporation: $233.90 billion
4. Phillips 66: $169.55 billion
5. Berkshire Hathaway Inc.: $162.46 billion

1. Wal-mart Stores: $476.29 billion
2. Exxon Mobil Corporation: $407.67 billion
3. Chevron Corporation: $220.36 billion
4. Berkshire Hathaway Inc.: $182.15 billion
5. Apple, Inc.: $170.91 billion

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1. Wal-mart Stores: $485.65 billion
2. Exxon Mobil Corporation: $382.60 billion
3. Chevron Corporation: $203.78 billion
4. Berkshire Hathaway Inc.: $194.67 billion
5. Apple, Inc.: $182.80 billion

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